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The oldest predaceous water bugs (Insecta, Heteroptera, Belostomatidae), with implications for paleolimnology of the Triassic Cow Branch Formation

Published online by Cambridge University Press:  05 September 2017

Julia Criscione
Affiliation:
Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ, 08854, USA 〈juliecriscione@gmail.com〉
David Grimaldi
Affiliation:
Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th St, New York, NY, 10024, USA 〈grimaldi@amnh.org〉

Abstract

A new genus and species of predaceous water bugs, Triassonepa solensis n. gen. n. sp., is described from the Triassic Cow Branch Formation of Virginia and North Carolina (USA) based on ~36 adult specimens and 51 nymphs. This species is the oldest known member of the extant family Belostomatidae. It is placed in a new genus based on the unique structure of the raptorial foreleg, in which the tarsus is elongate and opposed to the tibia + femur. The fossil record of this family is reviewed and the paleoenvironmental implications of the species assemblage preserved in the Cow Branch Formation are discussed.

Type
Articles
Copyright
Copyright © 2017, The Paleontological Society 

Introduction

The Heteroptera, or sucking bugs, have a long fossil record, potentially spanning back to the Permian. The first putative heteropteran from this period is Paraknightia magnifica Evans, Reference Evans1943 from New South Wales (Evans, Reference Evans1950). However, the first definitive heteropteran, Arlecoris louisi Shcherbakov, Reference Shcherbakov2010, was recently described from the earliest Middle Triassic (early Anisian) of the northern Vosges Mountains of France. This species is also the earliest member of the infraorder Nepomorpha Popov, Reference Popov1968, a group containing the majority of truly aquatic heteropterans (Belostomatidae Leach, Reference Leach1815; Nepidae Latreille, Reference Latreille1802; Naucoridae Leach, Reference Leach1815; Corixidae Leach, Reference Leach1815; and Notonectidae Leach, Reference Leach1815). The Nepomorpha have the best fossil record of all Heteroptera (Grimaldi and Engel, Reference Grimaldi and Engel2005), no doubt because of their aquatic habits, but the fossil record of belostomatids is not yet well studied. Modern Belostomatidae are medium- (9 mm) to very large-sized (110 mm adult body length) swimming bugs that are efficient predators, grabbing prey with raptorial forelegs, injecting potent salivary secretions, and siphoning out the liquefied internal tissues of their prey with a sharp beak.

The earliest described belostomatid fossils are from the Jurassic, when the family first diversified. The oldest of these is Odrowazicoris polonicus Popov, Reference Popov1996, an isolated wing in Hettangian-age beds of the Holy Cross Mountains of Poland. A number of other Jurassic species have been described from Europe and the United States, including: Tarsabedus menkei Popov, Dolling, and Whalley, Reference Popov, Dolling and Whalley1994; Aenictobelostoma primitivum Polhemus, Reference Polhemus2000; Stygeonepa foersteri Popov, Reference Popov1971; and Nettelstedtia breitkreutzi Popov, Rust, and Brauckmann, Reference Popov, Rust and Brauckmann2000. The Early Cretaceous also harbored diverse species and genera, including three taxa from the Crato Formation Plattenkalk of Brazil, and a species possessing unique paddle-shaped metathoracic legs, Iberonepa romerali Martínez-Delclòs, Nel, and Popov, Reference Martínez-Delclòs, Nel and Popov1995, from Las Hoyas, Spain.

Though belostomatids are widespread in Cenozoic sediments, many are still undescribed, including a Paleocene specimen from Alberta, Canada (Mitchell and Wighton, Reference Mitchell and Wighton1979), two unnamed early Eocene specimens from Denmark (Larsson, Reference Larsson1975; Rust and Ansorge, Reference Rust and Ansorge1996), and a late Oligocene specimen from Germany (Wedmann, Reference Wedmann2000). The extant genus Lethocerus Mayr, Reference Mayr1853 became fairly diverse during the Miocene, with two species (L. sulcifemoralis Říha and Kukalová, 1967, and L. turgaicus Popov, Reference Popov1971) found in the Oligocene–Miocene of the Czech Republic and the Miocene of Russia, respectively. Additionally, two modern species, Lethocerus americanus Leidy, Reference Leidy1847 and Belostoma bakeri Montandon, Reference Montandon1913, are reported to occur in Late Pleistocene asphalt deposits of California (Miller, Reference Miller1983). See Table 1 for a complete list of fossil belostomatid species.

Table 1 List of fossil belostomatid species.

Today, belostomatids have a worldwide distribution, although the majority of species are found in the tropics. They are represented by three subfamilies consisting of nine genera and ~146 species (Schuh and Slater, Reference Schuh and Slater1995). The subfamily Belostomatinae Lauck and Menke, Reference Lauck and Menke1961, is by far the largest group within Belostomatidae and contains six genera: Abedus Stål, Reference Stål1862; Appasus Amyot and Serville, Reference Amyot and Serville1843 (Polhemus, Reference Polhemus1995); Belostoma Latreille, Reference Latreille1807; Diplonychus Laporte, Reference Laporte1833; Hydrocyrius Spinola, Reference Spinola1850; and Limnogeton Mayr, Reference Mayr1853. The subfamily Horvathiniinae Lauck and Menke, Reference Lauck and Menke1961, is monogeneric, consisting of nine species in the genus Horvathinia Montadon, Reference Montandon1911. The third subfamily, Lethocerinae Lauck and Menke, Reference Lauck and Menke1961, consists of three genera: Lethocerus Mayr, Reference Mayr1853; Benacus Stål, Reference Stål1861 (Goodwyn, Reference Goodwyn2006); and Kirkaldyia Montandon, Reference Montandon1909 (Goodwyn, Reference Goodwyn2006).

The current belostomatid phylogeny is based on morphology and reproductive behaviors: (Lethocerinae, (Horvathiniinae (Belostomatinae))) (Lauck and Menke, Reference Lauck and Menke1961; Mahner, Reference Mahner1993; Smith, Reference Smith1997). Lethocerinae is the most basal taxon because it retains many characters of Nepidae (‘water scorpions’), the sister group to Belostomatidae. In addition, all species of Lethocerinae are emergent-brooders, meaning that their eggs are deposited on emergent vegetation and attended to by the males. In contrast, the more derived members of Belostomatinae are back-brooders, in which eggs are deposited on the backs of their male mates. Horvathiniinae is placed between Lethocerinae and Belostomatinae because of its more intermediate morphological characteristics. Brooding behavior has not been observed in this group and its phylogenetic position is less certain (Lauck and Menke, Reference Lauck and Menke1961).

The relationships within subfamily Belostomatinae are mostly resolved based on morphology, with the exception of the genus Limnogeton. Its position has been questioned due to its lack of raptorial forelegs and natatorial mid and hind legs. Lauck and Menke (Reference Lauck and Menke1961) noted the possibility that these characters may indicate a more basal position within Belostomatidae. However, it has been placed within subfamily Belostomatinae because it exhibits back-brooding behavior (Voelker, Reference Voelker1968). This position was supported in a recent phylogenetic analysis of Nepomorpha (Brożek, Reference Brożek2014).

This paper describes the earliest known species of family Belostomatidae, Triassonepa solensis n. gen. n. sp., from the Late Triassic Cow Branch Formation of southern Virginia and northern North Carolina. Based on both the species assemblage within the formation and the known habitats of modern belostomatids, probable chemical and environmental conditions of the deposit are discussed.

Materials and methods

Locality and material

The fossils described in this study are from the Cow Branch Formation of southern Virginia and northern North Carolina, a Late Triassic (Carnian/early Norian, 230–220 Ma) deposit outcropping in the former Solite Quarry where >30 Van Houten cycles are preserved. Three cycles have yielded insect fossils, but one cycle has produced the majority of the insects in this formation (Olsen et al., Reference Olsen, Remington, Cornet and Thomson1978; Fraser et al., Reference Fraser, Grimaldi, Olsen and Axsmith1996). The Cow Branch Formation is significant because it preserves the oldest fauna of freshwater insects, which are preserved as thin, two-dimensional, silvery films in a matrix of very fine-grained, black shale. Preservation is often excellent, with many specimens fully articulated and microscopic details visible. In addition to 11 orders of insects (Fraser and Grimaldi, Reference Fraser and Grimaldi2003; Grimaldi et al., Reference Grimaldi, Junfeng, Fraser and Rasnitsyn2005), the Solite Quarry has produced numerous amphibious reptiles (Tanytrachelos ahynis Olsen, Reference Olsen1979), a gliding reptile (Mecistotrachelos apeoros Fraser et al., Reference Fraser, Olsen, Dooley and Ryan2007), fish fossils, dinosaur footprints, and many plant species (Olsen et al., Reference Olsen, Remington, Cornet and Thomson1978).

Methods

Specimens were viewed using a Nikon SMZ1500 microscope, fitted with a fiber optic ring light. This non-directional, diffuse light source was necessary to illuminate the silvery, carbonized film by which the insects are preserved. In order to examine the minute details, specimens were wetted with 70% ethanol to increase contrast between the fossil and the black shale matrix. Photographs were taken using two separate setups. Specimens viewed at the American Museum of Natural History (AMNH) were photographed with a Nikon 16MP camera and Nikon Elements NIS software on a Nikon SMZ1500 stereomicroscope. Specimens housed at the Virginia Museum of Natural History (VMNH) were photographed with a Canon 6D DSLR camera using Canon Utility 2 software. All specimen measurements were taken using ImageJ software. Total lengths of adults were measured from the anterior margin of head to the distal margin of the 7th abdominal segment, in order to exclude the 8th abdominal segment, which protrudes to varying degrees in different specimens.

Repositories and institutional abbreviations

Most of the material examined in this study is housed at the Virginia Museum of Natural History (VMNH), Martinsville, Virginia, USA; some specimens are deposited in the American Museum of Natural History (AMNH), New York, USA.

Systematic paleontology

Suborder Heteroptera Latreille, Reference Latreille1810

Infraorder Nepomorpha Popov, Reference Popov1968

Superfamily Nepoidea Latreille, Reference Latreille1802

Family Belostomatidae Leach, Reference Leach1815

Genus Triassonepa new genus

Type species

Triassonepa solensis n. gen. n. sp. by present designation.

Diagnosis

As for type species, by monotypy.

Etymology

The genus name is a combination of the prefix Triasso-, for the Triassic Period from which the genus is derived, and -nepa, a standard suffix used for the superfamily Nepoidea.

Occurrence

Former Solite Quarry C, Eden, Rockingham County, North Carolina, USA (36°32'29.6556''N, 79°40'12.8424''W); Carnian/Norian, Late Triassic, Cow Branch Formation.

Remarks

Triassonepa n. gen. differs from all other known extinct and extant genera of Belostomatidae by the structure of the foreleg, in which the tarsus is elongate and opposed to the tibia + femur.

Triassonepa solensis new genus new species

Figures 15

Figure 1 Triassonepa solensis n. gen. n. sp., habitus of holotype, VMNH 94671. Scale bar is 2 mm.

Figure 2 Photographs of adult specimens of Triassonepa solensis n. gen. n. sp.: (1) VMNH 49641; (2) VMNH 53881; (3) VMNH 53880; (4) VMNH 94672. Scale bars are 2 mm.

Figure 3 Reconstruction of Triassonepa solensis n. gen. n. sp. showing major morphological characters.

Figure 4 Morphological comparison of the forelegs, hemelytra, metathoracic legs, and terminalia of adult Triassonepa solensis n. gen. n. sp. and extant belostomatid species: (1) foreleg, VMNH 94671, holotype; (2) foreleg, Belostoma flumineum Say, Reference Say1832; (3) foreleg, Benacus griseus (Say, Reference Say1832) (formerly genus Lethocerus); (4) hemelytra, VMNH 53881; (5) hemelytra, Diplonychus urinator sudanensis Linnavuori, Reference Linnavuori1971; (6) setal fringe on metathoracic leg, VMNH 50230; (7) setal fringe on metathoracic leg, Belostoma elongatum Montandon, Reference Montandon1908; (8) double setal fringe on metathoracic leg, VMNH 90281; (9) double setal fringe on metathoracic leg, VMNH 90279; (10) metathoracic leg, VMNH 94671, holotype; (11) female terminalia, VMNH 90281; (12) male terminalia, VMNH 94671, holotype; (13) terminalia, Diplonychus urinator sudanensis Linnavuori, Reference Linnavuori1971. Scale bars are 1 mm.

Figure 5 Triassonepa solensis n. gen. n. sp. growth series: (1) Instar I, VMNH 94575a; (2) Instar II, VMNH 50512; (3) Instar III, VMNH 53871; (4) Instar IV, VMNH 54155; (5) Instar V, VMNH 52498. Scale bar is 2 mm, located in photo 1.

Holotype

VMNH 94671, male, Fig. 1.

Diagnosis

Body elongate. Head small, largely hidden beneath pronotum dorsally, with triangular clypeus. Pronotum small with concave anterior and posterior margins. Hemelytra with prominent claval suture; dense reticulations on apical third. Prothoracic legs raptorial, with elongate tarsus opposed to tibia. Metathoracic tibia and tarsus with dense setal fringe on inner (mesal) margin. Abdomen with seven visible segments (segments 2–8) and five visible pairs of spiracles.

Occurrence

Former Solite Quarry C, Eden, Rockingham County, North Carolina, USA (36°32'29.6556''N, 79°40'12.8424''W); Carnian/Norian, Late Triassic, Cow Branch Formation.

Description of Adults

The description is based on the ~36 adult specimens collected to date (Fig. 2). Body elongate; total length (anterior margin of head, excluding clypeus, to apex of 7th abdominal segment) 10.6–14.1 mm (mean 12.1 mm).

Head

Small, largely hidden beneath pronotum dorsally, with triangular clypeus. Eyes, antennae, and mouthparts not visible. Ocelli, if present, not visible.

Thorax

Pronotum small, 2.5–3.5 mm wide, 0.8–1.1 mm long, with concave anterior and posterior margins. Mesonotum width ~1.6x pronotum width; possible pigmentation preserved on pronotum and mesonotum. Scutellum about as wide as pronotum, but with indistinct margins. Hemelytra with fine crenulations on proximal two-thirds, reticulations on distal third; clavus and claval suture distinct; venation as shown in Figure 3 (also Fig. 4.4). Hindwing, if present, not preserved. Prothoracic legs raptorial (Fig. 4.1); femur wide at base (~1 mm), narrowed distally, partially obscured by body; tarsus elongate and opposed to tibia, tibia and tarsus of similar width, tibia length ~1.1x length of tarsus; tarsal claw not visible. Mesothoracic legs slender, with no setae or fringe apparent; tibia ~1.3x length of entire tarsus. Metathoracic legs slender, with dense setal fringe on inner (mesal) margin of tibia and tarsus (Fig. 4.6); few specimens with double setal fringe on tarsus (Fig. 4.8, 4.9); femur partially obscured by body; tibia length ~1.2x tarsus length; tarsus with two segments.

Abdomen

Broad, often obscured by hemelytra; length (7.4–8.6 mm) and width (5.4–6.3 mm) vary, likely due to diagenetic alteration; abdominal segments 2–8 visible; dorsum with five pairs of spiracles visible on segments 3–7. Spiracle diameter ranges from 0.26 to 0.40 mm (mean 0.34 mm). Terminalia variable, but with lateral paddle-like lobes; pair of short processes between the lobes that resemble respiratory tubes; two specimens (VMNH 94671, Fig. 4.12, holotype; VMNH 94672, Fig. 2.4) with more elongate terminalia and two distal articulated appendages, possibly claspers.

Description of nymphs

The description is based on 51 nymph specimens. Body oval, narrowed at anterior and posterior ends. Head small, often not preserved, no features discernable. Thorax roughly trapezoidal with dividing line between lateral halves; wing pads not visible. Prothoracic and mesothoracic legs not preserved. Few specimens with metathoracic tarsus preserved; setal fringe present, as in adults; two specimens (e.g., VMNH 54155, Fig. 5.4) with double setal fringe; claws, if present, not visible. Abdomen roughly triangular; six segments visible (segments 3–8).

Etymology

The specific epithet is named after the former Virginia Solite Corporation quarries, from which the specimens were recovered.

Remarks

Specimen VMNH 94671 was chosen as the holotype because of the excellent preservation of its legs (Fig. 1). It is the only specimen yet found with a preserved foreleg, and one of only two specimens with a preserved mesothoracic leg. Though this specimen has a narrower abdomen and lacks the stoutness of the other specimens, this difference in overall shape can likely be attributed to diagenesis due to its morphologic similarity to the other specimens. Additionally, it is the largest specimen (14.10 mm), but it is of a similar size to that of the only other male specimen (VMNH 94672, Fig. 2.4, 13.49 mm). This may indicate that males of this species were larger than the females, which is unusual in the Heteroptera.

Triassonepa solensis n. gen n. sp. is the earliest known member of the family Belostomatidae. Unfortunately, all adult specimens are preserved in dorsal aspect, concealing many morphological characters. This is interesting because preservation of the ventral surface is quite common in other belostomatid fossils (e.g., Sinobelostoma liui, Chou and Hong, Reference Chou and Hong1989; Lethocerus vetus, Nel and Waller, Reference Nel and Waller2006). Triassonepa solensis n. gen. n. sp. ranges in length from ~10.6–14.1 mm, placing it on the small side of the range of modern belostomatids (9–110 mm; Schuh and Slater, Reference Schuh and Slater1995).

The head of Triassonepa solensis n. gen. n. sp. is poorly preserved in almost all specimens, preventing a detailed description at this time. The only feature often visible is the triangular clypeus. Neither compound eyes nor ocelli are preserved, although the absence of ocelli may be expected since modern belostomatids do not possess them (Lauck and Menke, Reference Lauck and Menke1961). The absence of preserved antennae is also expected given that the antennae of modern belostomatids are small and concealed within grooves beneath their heads (Schuh and Slater, Reference Schuh and Slater1995). In addition, due to the exclusive preservation of the dorsal surface, no mouthparts are visible.

The legs of Triassonepa solensis n. gen. n. sp. provide some interesting characters for comparison with modern members of the Belostomatidae. One unique character of this species is the structure of its prothoracic legs (Fig. 4.1). Though only preserved in a single specimen, the foreleg of T. solensis has an elongate tarsus that opposes the tibia. In contrast, modern belostomatids have a thin tibia + tarsus opposed to the femur (Fig. 4.2, 4.3). This raptorial foreleg appears to be less specialized than those of modern belostomatids. Another difference between T. solensis and modern belostomatids is the possession of setae on the legs. Modern belostomatids have setae on both the mesothoracic and metathoracic legs, but it appears that the mesothoracic legs of T. solensis lack these setae. This might suggest that instead of using these legs for swimming, they may have used them in conjunction with the forelegs to capture and hold prey. However, only three mesothoracic legs on two specimens have been recovered to date, indicating that the absence of these setae is not yet definitive. Triassonepa solensis n. gen. n. sp. does, however, possess a setal fringe on the metathoracic legs (Fig. 4.6, 4.8–4.10), indicating that they were specialized swimmers. It is interesting to note that a few specimens (including two nymphs) appear to have a double setal-fringe (Fig. 4.8, 4.9). It is unclear at this time whether this double-fringe is a result of the position in which they were preserved, or if these specimens are a distinct species. Measurements of body length, abdomen width, and tarsal length have shown that these two specimens have similar proportions to specimens with a single fringe, and therefore may be the same species.

The hemelytra of Triassonepa solensis n. gen. n. sp. also provide good features for comparison to modern taxa. The hemelytra do not appear to cover the entire abdomen of any specimen, but this is likely an artifact of preservation (Fig. 4.4). Because the apical parts of modern heteropteran hemelytra are thin and membranous, it is unlikely that these regions would have been preserved. In addition, the abdominal spiracles of T. solensis are located on its dorsal surface, which is typical of insects that breathe underwater via a plastron (a thin film of air held beneath the wings and used as a physical gill). In order for T. solensis to use a plastron, as is done by many modern aquatic insects including belostomatids (e.g., Abedus herberti Hildago, Reference Hildago1935; see Goforth and Smith, Reference Goforth and Smith2012), its hemelytra would need to fully cover its spiracles (i.e., to the edges of the abdomen).

The 8th abdominal segment of Triassonepa solensis n. gen. n. sp. contains two lateral, paddle-shaped lobes and two medial processes resembling respiratory tubes (Fig. 4.11). It is morphologically quite similar to the eighth abdominal segment of female naucorids (particularly Ilyocoris exclamationis Scott, Reference Scott1874 as illustrated by Lee, Reference Lee1991). This suggests that: (1) T. solensis occupies a very basal position within Belostomatidae, and (2) the majority of the preserved specimens were likely female. However, two specimens (VMNH 94671, Fig. 4.12, holotype; VMNH 94672, Fig. 2.4) possess terminalia with a slightly different structure. The 8th abdominal segments of these specimens are more elongate and possess two apical, articulated appendages that resemble claspers. It is therefore likely that these two specimens are males.

Immature Triassonepa solensis n. gen. n. sp. were separated into instars based on total body lengths (Fig. 5). Because the head was not often preserved, there is a minor amount of uncertainty in some of the measurements. A total of 51 nymphs were measured from the anterior margin of the head to the apex of the abdomen, yielding five size classes (Fig. 6): Instar I, 1.6–2.3 mm (mean 2.0 mm); Instar II, 2.6–3.4 mm (mean 3.0 mm); Instar III, 4.0–5.2 mm (mean 4.6 mm); Instar IV, 6.2–7.7 mm (mean 6.9 mm); Instar V, 9.5–10.3 mm (mean 9.9 mm). Each instar was ~1.5x larger than the preceding one. Modern belostomatids also have five instars and show a similar growth ratio of 1.2–1.5 with each successive instar (Tables 2, 3). These ratios correspond to Dyar’s Rule, which states that an insect instar is ~1.4x the size of its previous instar.

Figure 6 Lengths of Triassonepa solensis n. gen. n. sp. instars and adults: 70 specimens (51 nymphs, 19 adults) were measured. The two largest adult specimens are males.

Table 2 Mean lengths (in mm) of the five instars of Triassonepa solensis n. gen. n. sp. (this study), Lethocerus maximus (Cullen, Reference Cullen1969), L. mazzai (De Carlo, Reference De Carlo1962), Hydrocyrius columbiae (Miller, Reference Miller1961), Belostoma flumineum (Flosi, Reference Flosi1980), B. malkini (Cullen, Reference Cullen1969), and Abedus breviceps (Keffer and McPherson, Reference Keffer and McPherson1988).

Table 3 Growth ratios Triassonepa solensis n. gen. n. sp. (this study), Lethocerus maximus (Cullen, Reference Cullen1969), L. mazzai (De Carlo, Reference De Carlo1962), Hydrocyrius columbiae (Miller, Reference Miller1961), Belostoma flumineum (Flosi, Reference Flosi1980), B. malkini (Cullen, Reference Cullen1969), and Abedus breviceps (Keffer and McPherson, Reference Keffer and McPherson1988) (the same species as in Table 2), calculated by dividing instar length by length of the previous instar.

Discussion

Belostomatid habitats

Due to the presence of swimming fringes on the hind legs of Triassonepa solensis n. gen. n. sp., it is reasonable to assume that this species had similar physiology and behaviors to modern belostomatids. Understanding the habitats of these modern belostomatids has implications for determining the nature and chemistry of ancient ‘Lake Solite.’

Belostomatids live in a wide variety of habitats, but are most commonly found in shallow bodies of water with marginal vegetation. Kashian and Burton (Reference Kashian and Burton2000) reported Lethocerus sp. from the wetlands of northern Lake Huron in areas dominated by sedges. Belostomatids also occur in many of India’s small freshwater lakes. Majumder et al. (Reference Majumder, Das, Majumder, Ghosh and Agarwala2013), for example, found two genera (Lethocerus and Diplonychus) living in the marginal vegetation of manmade, urban lakes in Tripura, northeastern India. Diplonychus rusticus Fabricius, Reference Fabricius1781 was collected from both Pocharam Lake in southeastern India (Deepa and Rao, Reference Deepa and Rao2007), and Loktak Lake of northeastern India (Takhelmayum and Gupta, Reference Takhelmayum and Gupta2011). Loktak Lake is unique in its possession of phumdis, which are floating islands composed of vegetation, organic matter, and soil, among which belostomatids live. Belostomatids have also been collected from arid wetlands such as Bañado Carilauquen in west-central Argentina (Scheibler and Ciocco, Reference Scheibler and Ciocco2013). These semi-permanent wetlands are located near a shallow, saline lake, although the wetlands themselves have negligible salinity.

In addition to shallow lakes and wetland environments, belostomatids inhabit the marginal areas of deep lakes, such as Lake Victoria in Kenya (Muli and Mavuti, Reference Muli and Mavuti2001; Orwa et al., Reference Orwa, Omondi, Ojwang and Mwanchi2015). Three species were identified there: Diplonychus sp. (formerly genus Sphaerodema), Hydrocyrius sp., and Lethocerus niloticus Stål, Reference Stål1885. Similarly to Loktak Lake, Diplonychus sp. and Hydrocyrius sp. were found to inhabit the lake’s floating hyacinth mats (Orwa et al., Reference Orwa, Omondi, Ojwang and Mwanchi2015).

Belostomatids are one of the few groups of aquatic insects that can tolerate agriculture-affected and polluted water bodies. Belostomatids inhabit the length of the Enfranz River in Ethiopia, from the clean headwaters to the agriculture-dominated mouth (Mehari et al., Reference Mehari, Wondie, Mingist and Vijverberg2014). Other nepomorphs, such as naucorids and nepids, were only found in the unaffected, upstream areas. Additionally, Belostoma sp. has been collected in the eutrophic Kipkaren River of Kenya (Aura et al., Reference Aura, Raburu and Herrmann2011) and Diplonychus sp. was found to inhabit the margins of a number of polluted Bangalore lakes in southern India (Balachandran and Ramachandra, Reference Balachandran and Ramachandra2010). Perhaps the most extreme case is the collection of Belostoma sp. from hydrogen sulfide-rich Cueva del Azufre in Tabasco, Mexico (Tobler et al., Reference Tobler, Schlupp and Plath2007).

Belostomatids are also known to inhabit temporary environments such as rain pools (Fontanarrosa et al., Reference Fontanarrosa, Collantes and Bachmann2009), agricultural fields (Das and Gupta, Reference Das and Gupta2010), rice paddies (Hendawy et al., Reference Hendawy, Sherif, Abada and El-Habashy2005), and sinkholes (Blinn and Sanderson, Reference Blinn and Sanderson1989), and are common inhabitants of ephemeral playa lakes in arid environments (Haukos and Smith, Reference Haukos and Smith1992). Belostomatids have been collected in the stagnant ‘buffalo-wading pools’ of Tarangire National Park on the savanna of northern Tanzania (D.G., personal observation). Merickel and Wangberg (Reference Merickel and Wangberg1981) collected Belostoma flumineum along the shores of two playas near Lubbock, Texas, and Richardson et al. (Reference Richardson, Ward and Huddleston1972) found one juvenile belostomatid in the Jornada Playa of New Mexico. Adult belostomatids disperse to these ephemeral environments via flight, and as a result, are often found at bright lights during the night.

A few studies have even reported belostomatids inhabiting brackish waters. Angelin et al. (Reference Angelin, Jehamalar, Das and Kumar2010) collected Diplonychus sp. and Belostoma sp. from an estuary in southern India with a salinity of between 4‰ and 8‰ (ppt). Siddiqi (Reference Siddiqi2008) reported belostomatids in the marginal areas of India’s Lake Lonar, which is a hyperalkaline, saline, crater lake with a pH of ~10.5 (Siddiqi, Reference Siddiqi2008) and a salinity of up to ~6‰ (Yannawar and Bhosle, Reference Yannawar and Bhosle2013). However, Badve et al. (Reference Badve, Kumaran and Rajshekhar1993) report that the marginal areas of the lake near the inflow of the freshwater springs have a pH closer to 7.5. It is in these areas that the marshes exist, and it is likely that the belostomatids inhabit these more suitable areas.

Environmental interpretation of ‘Lake Solite’

Like their modern counterparts, many fossil belostomatids are reported from shallow, lacustrine paleoenvironments (e.g., Grimaldi and Maisey, Reference Grimaldi and Maisey1990; Martínez-Delclòs et al., Reference Martínez-Delclòs, Nel and Popov1995; Prokop and Nel, Reference Prokop and Nel2000). However, this contrasts with both interpretations of the paleoenvironment of the Cow Branch Formation. Olsen et al. (Reference Olsen, Remington, Cornet and Thomson1978) first described the environment as a large, deep, chemically stratified lake. This stratification would have produced anoxic bottom waters that prevented bioturbation and therefore allowed for exquisite fossil preservation of delicate insects such as midges and tiny hemipterans. Although unusual for a modern belostomatid habitat, other deep lacustrine paleoenvironments have been reported to contain belostomatid fossils. One such deposit, the late Oligocene Enspel Formation of Germany (Poschmann et al., Reference Poschmann, Schindler and Uhl2010), has produced ten belostomatid fossils, four of which are adult specimens (Wedmann, Reference Wedmann2000).

Recent research by Liutkus et al. (Reference Liutkus, Beard, Fraser and Ragland2010) proposed that the Cow Branch Formation was a shallow, alkaline, saline, rift valley lake. They presented a number of reasons for this interpretation: (1) dominance of terrestrial and nearshore-dwelling insects and terrestrial vascular plants, (2) exquisite fossil preservation, and (3) presence of dolomite and absence of quartz and zirconium throughout the deposit.

Based on the environmental preferences of modern belostomatids, their abundance in the Cow Branch Formation would indicate a shallow, nearshore paleoenvironment. The tolerance of modern belostomatids for polluted and harsh water conditions suggests they may have also been tolerant to extreme environments such as saline, alkaline, rift valley lakes. Because belostomatids breathe air, they would be unaffected by poor water quality. However, harsh water conditions would affect organisms possessing gill respiration (i.e., Ephemeroptera, Plecoptera, Odonata, Trichoptera, etc.), so the lack of gilled insect nymphs of these orders within the deposit is good evidence for poor water quality. The only gilled insect order reported from the Cow Branch Formation is Diptera (Liutkus et al., Reference Liutkus, Beard, Fraser and Ragland2010). However, this appears to be a misidentification of the enigmatic, gilled, larva-like arthropod, which may actually be a crustacean.

In addition to belostomatids, the insects preserved in the Cow Branch Formation are mostly terrestrial adults from the orders Hemiptera (Sternorrhyncha), Diptera, and Coleoptera. A few other taxa have been found to date, including adult members of Blattodea, Odonata, Orthoptera, Plecoptera (Fraser and Grimaldi, Reference Fraser and Grimaldi2003), Thysanoptera (Grimaldi et al., Reference Grimaldi, Shmakov and Fraser2004), Mecopterida (Grimaldi et al., Reference Grimaldi, Junfeng, Fraser and Rasnitsyn2005), Amphiesmenoptera, and Neuroptera. This unique assemblage of terrestrial insects further suggests that the water was toxic to gill-possessing, aquatic larvae and other sensitive groups. Moreover, Fraser and Grimaldi (Reference Fraser and Grimaldi1999) noted the abundance of conchostracans within the insect bed. Modern members of this group are most commonly found in ephemeral, alkaline water bodies (Tasch, Reference Tasch1969).

Liutkus et al. (Reference Liutkus, Beard, Fraser and Ragland2010) discussed the exquisite preservation of the insect fossils as evidence for a shallow lake. Most insects are completely articulated, which is quite rare for Triassic fossils (cf., Riek, Reference Riek1974; Brauckmann and Schlüter, Reference Brauckmann and Schlüter1993; Shcherbakov et al., Reference Shcherbakov, Lukashevich and Blagoderov1995; Martins-Neto et al., Reference Martins-Neto, Gallego and Zavattieri2008). The lack of disarticulation suggests limited postmortem movement. If the lake had been as deep as originally suggested, the insects would likely have decayed, disarticulated, or have been eaten before settling to the benthic zone. Moreover, there are no fossil fish found in the insect layers, further evidence that the insects were buried in very shallow water.

The geochemistry of the deposit also supports the interpretation of a saline, alkaline lake. Liutkus et al. (Reference Liutkus, Beard, Fraser and Ragland2010) reported dolomitic claystone throughout the insect bed, and in modern lakes primary precipitation of dolomite occurs most often in waters with elevated salinity, alkalinity, and with abundant magnesium and calcium (DeDeckker and Last, Reference De Deckker and Last1989). Furthermore, the surrounding basin is rich in quartz, making its absence in the Cow Branch deposit significant. In addition, albite is abundant in the deposit (Liutkus et al., Reference Liutkus, Beard, Fraser and Ragland2010), which is proposed to have formed by the reaction of clay, quartz, and sodium under alkaline conditions (van de Kamp and Leake, Reference van de Kamp and Leake1996). The deposit is also depleted in zirconium. Ayers and Zhang (Reference Ayers and Zhang2005) have demonstrated that this element dissolves in alkaline conditions. These three geochemical conditions support a saline, alkaline environment during the time of deposition.

Although most fossil belostomatids have been reported from shallow, non-saline, lacustrine environments, Polhemus (Reference Polhemus2000) reported fossils from a saline environment, the Jurassic Todilto Formation of New Mexico. This formation is interpreted as a paralic, saline playa due to its interfingered marine and continental sediments (Lucas et al., Reference Lucas, Rinehart and Estep2000). Although this interpretation is somewhat controversial, the water chemistry in this type of environment may have been similar to that proposed by Liutkus et al. (Reference Liutkus, Beard, Fraser and Ragland2010) for the Cow Branch Formation. Vega et al. (Reference Vega, García-Barrera, Perrilliat, Coutiño and Mariño-Pérez2006) gave a second example of a potentially saline belostomatid habitat from the Early Cretaceous Sierra Madre Formation of southeastern Mexico, which has been interpreted as a brackish marginal lagoon or estuary. Due to the wide environmental tolerances of both fossil and modern belostomatids, the dominance of terrestrial adult insects and lack of aquatic nymphs, the abundance of conchostracans, the exquisite preservation of the Solite fossils, and the geochemistry of the Cow Branch Formation, it is very likely that ‘Lake Solite’ was a shallow, saline, alkaline rift valley lake.

Acknowledgments

J.C. is grateful to the American Museum of Natural History Grants Program for the Theodore Roosevelt Memorial Grant, which provided the funding necessary to visit and collect at the Solite deposit. J.C. is especially grateful to C. Byrd for hosting her visits to the Virginia Museum of Natural History and to R. Vodden (VMNH) for allowing her to participate in the fossil excavation at the Solite deposit. We are grateful for the thoughtful commentary on this manuscript provided by B.W. Smith and an anonymous reviewer. Financial research support for this project came from a Graduate Teaching Assistantship from the Department of Earth and Planetary Sciences, Rutgers University.

References

Amyot, C.J.-B., and Serville, A., 1843, Histoire naturelle des insectes Hémiptères: Paris, Librairie Encyclopédique de Roret, 675 p.CrossRefGoogle Scholar
Angelin, J.A., Jehamalar, E.E., Das, S.S.M., and Kumar, S.P., 2010, Effect of salinity on the distribution of aquatic insects of Manakudy Estuary, Kanyakumari District: Journal of Basic and Applied Biology, v. 4, p. 9197.Google Scholar
Aura, C.M., Raburu, P.O., and Herrmann, J., 2011, Macroinvertebrates’ community structure in Rivers Kipkaren and Sosiani, River Nzoia basin, Kenya: Journal of Ecology and the Natural Environment, v. 3, p. 3946.Google Scholar
Ayers, J.C., and Zhang, L., 2005, Zircon aqueous solubility and partitioning systematics: Goldschmidt Conference Abstracts, Moscow, v. 15, p. A5.Google Scholar
Badve, R.M., Kumaran, K.P.N., and Rajshekhar, C., 1993, Eutrophication of Lonar Lake, Maharashtra: Current Science, v. 65, p. 347351.Google Scholar
Balachandran, C., and Ramachandra, T.V., 2010, Aquatic macroinvertebrate diversity and water quality of Bangalore lakes. Lake 2010: Wetlands, Biodiversity and Climate Change, 22–24 December, Satish Dhawan Auditorium, Indian Institute of Science, Bangalore, p. 1–18. http://wgbis.ces.iisc.ernet.in/energy/lake2010/Theme 1/balachandran.pdf Google Scholar
Blinn, D.W., and Sanderson, M.W., 1989, Aquatic insects in Montezuma Well, Arizona, USA: a travertine spring mound with high alkalinity and dissolved carbon dioxide: The Great Basin Naturalist, v. 49, p. 8588.Google Scholar
Brauckmann, C., and Schlüter, T., 1993, Neue Insekten aus der Trias von Unter-Franken: Geologica et Palaeontologica, v. 27, p. 181199.Google Scholar
Brożek, J., 2014, Phylogenetic signals from Nepomorpha (Insecta: Hemiptera: Heteroptera) Mouthparts: Stylets Bundle, Sense Organs, and Labial Segments: The Scientific World Journal, v. 2014, p. 130.Google Scholar
Chou, I., and Hong, Y., 1989, An Early Cretaceous new genus and species in Shaanganning Basin (Insecta: Heteroptera): Entomotaxonomia, v. 11, p. 197205. [in Chinese with English Summary]Google Scholar
Cullen, M.J., 1969, The biology of giant water bugs (Hemiptera: Belostomatidae) in Trinidad: Proceedings of the Royal Entomological Society of London, Series A, v. 44, p. 123–136.CrossRefGoogle Scholar
Das, K., and Gupta, S., 2010, Aquatic Hemiptera community of agricultural fields and rain pools in Cachar District, Assam, North East India: Assam University Journal of Science and Technology, v. 5, p. 123128.Google Scholar
De Carlo, J.M., 1962, Consideraciones sobre la biologia de Lethocerus mazzai De Carlo (Hemiptera: Belostomatidae): Physis, v. 23, p. 143151.Google Scholar
De Deckker, P., and Last, W.M., 1989, Modern, non-marine dolomite in evaporitic playas of western Victoria, Australia: Sedimentary Geology, v. 64, p. 223238.Google Scholar
Deepa, J., and Rao, C.A.N., 2007, Aquatic Hemiptera of Pocharam Lake, Andhra Pradesh: Zoos’ Print Journal, v. 22, p. 29372939.Google Scholar
Evans, J.W., 1943, Upper Permian Homoptera from New South Wales: Records of the Australian Museum, v. 21, p. 180198.Google Scholar
Evans, J.W., 1950, A re-examination of an Upper Permian insect, Paraknightia magnifica Ev: Records of the Australian Museum, v. 22, p. 246250.Google Scholar
Fabricius, J.C., 1781, Species Insectorum Exhibentes Eorum Differntias Specificas, Synonyma Auctorum, Loca Natalia, Metamorphosis Adjectis Observationibus, Descriptionibus: Hafniae, Proft et Storch, v. 2, 517 p.Google Scholar
Flosi, J.W., 1980, The population biology of the giant water bug Belostoma flumineum Say (Hemiptera: Belostomatidae) [Ph.D. Thesis]: Ames, Iowa, Iowa State University, 161 p.Google Scholar
Fontanarrosa, M.S., Collantes, M.B., and Bachmann, A.O., 2009, Seasonal patterns of the insect community structure in urban rain pools of temperate Argentina: Journal of Insect Science, v. 9, p. 117.CrossRefGoogle ScholarPubMed
Fraser, N.C., and Grimaldi, D.A., 1999, A significant late Triassic Lagerstätte from Virginia, USA: Rivista del Museo Civico di Scienze Naturali “Enrico Caffi” v. 20 (supplement), p. 7984.Google Scholar
Fraser, N.C., and Grimaldi, D.A., 2003, Late Triassic continental faunal change: New perspectives on Triassic insect diversity as revealed by a locality in the Danville Basin, Virginia, Newark Supergroup, in Letourneau, P.M., and Olsen, P.E., eds., The Great Rift Valleys of Pangea in Eastern North America: New York, Columbia University Press, v. 2, p. 192205.Google Scholar
Fraser, N.C., Grimaldi, D.A., Olsen, P.E., and Axsmith, B., 1996, A Triassic Lagerstätte from eastern North America: Nature, v. 380, p. 615619.Google Scholar
Fraser, N.C., Olsen, P.E., Dooley, A.C. Jr., and Ryan, T.R., 2007, A new gliding tetrapod (Diapsida: ?Archosauromorpha) from the Upper Triassic (Carnian) of Virginia: Journal of Vertebrate Paleontology, v. 27, p. 261265.Google Scholar
Germar, E.F., 1839, Die versteinerten Insecten Solenhofens: Nova Acta Physico-Medica Academiae Caesareae Leopoldino-Carolinae Naturae Curiosum, v. 19, p. 187222.Google Scholar
Goforth, C.L., and Smith, R.L., 2012, Subsurface behaviours facilitate respiration by a physical gill in an adult giant water bug, Abedus herberti : Animal Behaviour, v. 83, p. 747753.CrossRefGoogle Scholar
Goodwyn, P.J.P., 2006, Taxonomic revision of the subfamily Lethocerinae Lauck & Menke (Heteroptera: Belostomatidae): Stuttgarter Beiträge zur Naturkunde, Serie A (Biologie), v. 695, p. 171.Google Scholar
Grimaldi, D., and Engel, M.S., 2005, Evolution of the Insects: New York, Cambridge University Press, 772 p.Google Scholar
Grimaldi, D., and Maisey, J., 1990, Introduction, in Grimaldi, D.A., ed., Insects from the Santana Formation, Lower Cretaceous, of Brazil: Bulletin of the American Museum of Natural History, p. 514.Google Scholar
Grimaldi, D., Shmakov, A., and Fraser, N., 2004, Mesozoic thrips and early evolution of the order Thysanoptera (Insecta): Journal of Paleontology, v. 78, p. 941952.Google Scholar
Grimaldi, D., Junfeng, Z., Fraser, N.C., and Rasnitsyn, A., 2005, Revision of the bizarre Mesozoic scorpionflies in the Pseudopolycentropodidae (Mecopteroidea): Insect Systematics & Evolution, v. 36, p. 443458.CrossRefGoogle Scholar
Haukos, D.A., and Smith, L.M., 1992, Ecology of Playa Lakes: Waterfowl Management Handbook, Paper 19, p. 1–7.Google Scholar
Hendawy, A.S., Sherif, M.R., Abada, A.E., and El-Habashy, M.M., 2005, Aquatic and semi-aquatic insects occurring in the Egyptian rice fields and hazardous effect of insecticides: Egyptian Journal of Agricultural Research, v. 83, p. 493502.Google Scholar
Hildago, J., 1935, The genus Abedus Stål (Hemiptera, Belostomatidae): The University of Kansas Science Bulletin, v. 22, p. 493519.Google Scholar
Kashian, D.R., and Burton, T.M., 2000, A comparison of macroinvertebrates of two Great Lakes coastal wetlands: testing potential metrics for an index of ecological integrity: Journal of Great Lakes Research, v. 26, p. 460481.CrossRefGoogle Scholar
Keffer, S.L., and McPherson, J.E., 1988, Descriptions of nymphal instars of Abedus breviceps (Hemiptera: Belostomatidae): Great Lakes Entomologist, v. 21, p. 169174.Google Scholar
Lakshminarayana, K.V., 1984, On some fossil Cryptocerata (Heteroptera: Insecta) with description of a new genus et species: Bulletin of the Zoological Survey of India, v. 5, p. 153158.Google Scholar
Laporte, F., 1833, Essai d’une classification systématique de l’ordre de Hémiptères (Hémiptères Hétéroptères, Latr.): Guerin Magasin de Zoologie, v. 2, p. 188.Google Scholar
Larsson, S.G., 1975, Palaeobiology and mode of burial of the insects of the Lower Eocene Mo-clay of Denmark: Bulletin of the Geological Society of Denmark, v. 24, p. 193209.Google Scholar
Latreille, P.A., 1802, Histoire naturelle, generale et particulière des crustaces et des insects, v. 3: Paris, F. Dufart, 467 p.CrossRefGoogle Scholar
Latreille, P. A., 1807, Genera crustaceorum et insectorum secundum ordinem naturalem in familias disposita, Iconibus Exemplisque Plurimus Explicata, v. 3: Paris, Amand Kœnig, 258 p.Google Scholar
Latreille, P.A., 1810, Considérations générales sur ll’ordre naturel des animaux: Paris, F. Schoell, 444 p.Google Scholar
Lauck, D.R., and Menke, A.S., 1961, The higher classification of the Belostomatidae (Hemiptera): Annals of the Entomological Society of America, v. 54, p. 644657.Google Scholar
Leach, W.E., 1815, Entomology, in Brewster, D., ed., The Edinburgh Encyclopaedia: Edinburgh, Blackwood, v. 9, p. 57172.Google Scholar
Lee, C.E., 1991, Morphological and phylogenetic studies on the true water bugs (Hemiptera: Heteroptera): Nature and Life, v. 21, 183 p.Google Scholar
Leidy, J., 1847, History and anatomy of the hemipterous genus Belostoma : Journal of the Academy of Natural Sciences of Philadelphia, v. 2, p. 5767.Google Scholar
Linnavuori, R., 1971, Hemiptera of the Sudan, with remarks on some species of the adjacent countries. I. The aquatic and subaquatic families: Annales Zoologici Fennici, v. 8, p. 340366.Google Scholar
Liutkus, C.M., Beard, J.S., Fraser, N.C., and Ragland, P.C., 2010, Use of fine-scale stratigraphy and chemostratigraphy to evaluate conditions of deposition and preservation of a Triassic Lagerstätte, south-central Virginia: Journal of Paleolimnology, v. 44, p. 645666.Google Scholar
Lucas, S.G., Rinehart, L.F., and Estep, J.W., 2000, Paleoecological significance of Middle Jurassic insect locality, Todilto Formation, north-central New Mexico, in Lucas, S.G., ed., New Mexico’s Fossil Record: New Mexico Museum of Natural History and Science, Bulletin 16, p. 2940.Google Scholar
Mahner, M., 1993, Systema Cryptoceratorum Phylogeneticum (Insecta, Heteroptera): Zoologica, v. 143, 302 p.Google Scholar
Majumder, J., Das, R.K., Majumder, P., Ghosh, D., and Agarwala, B.K., 2013, Aquatic insect fauna and diversity in urban fresh water lakes of Tripura, northeast India: Middle-East Journal of Scientific Research, v. 13, p. 2532.Google Scholar
Martínez-Delclòs, X., Nel, A., and Popov, Y.A., 1995, Systematics and functional morphology of Iberonepa romerali n. gen. and sp., Belostomatidae from the Spanish Lower Cretaceous (Insecta, Heteroptera): Journal of Paleontology, v. 69, p. 496508.Google Scholar
Martins-Neto, R.G., Gallego, O.F., and Zavattieri, A.M., 2008, The Triassic insect fauna from Argentina: Coleoptera, Hemiptera and Orthoptera from the Potrerillos Formation, south of Cerro Cacheuta, Cuyana basin: Alavesia, v. 2, p. 4758.Google Scholar
Mayr, G.L., 1853, Zwei neue Wanzen aus Kordofan, Limnogeton fieberi u. Lethrocerus cordofanus : Verhandlungen der Zoologisch-Botanischen Gesellschaft in Wien, v. 2, p. 1418.Google Scholar
Mehari, A.K., Wondie, A., Mingist, M., and Vijverberg, J., 2014, Spatial and seasonal variation in the macro-invertebrates and physico-chemical parameters of the Enfranz River, Lake Tana sub-basin (Ethiopia): Ecohydrology & Hydrobiology, v. 14, p. 304312.Google Scholar
Merickel, F.W., and Wangberg, J.K., 1981, Species composition and diversity of macroinvertebrates in two playa lakes on the Southern High Plains, Texas: The Southwestern Naturalist, v. 26, p. 153158.Google Scholar
Miller, P.L., 1961, Some features of the respiratory system of Hydrocyrius columbiae Spin. (Belostomatidae, Hemiptera): Journal of Insect Physiology, v. 6, p. 243271.Google Scholar
Miller, S.E., 1983, Late Quaternary insects of Rancho La Brea and McKittrick, California: Quaternary Research, v. 20, p. 90104.Google Scholar
Mitchell, P., and Wighton, D., 1979, Larval and adult insects from the Paleocene of Alberta, Canada: The Canadian Entomologist, v. 111, p. 777782.Google Scholar
Montandon, A.L., 1908, Nouvelles espèces d Hémiptères aquatiques: Annales Historico Naturales-Musei Nationalis Hungarici, v. 6, p. 299304.Google Scholar
Montandon, A.L., 1909, Belostomidae et Nepidae, Notes diverses et descriptions d’espèces nouvelles: Bulletin de la Société des Sciences, Bucarest, v. 18, p. 137147.Google Scholar
Montandon, A.L., 1911, Deux genres nouveaux d ́Hydrocorises: Annals of the Museum Nationalis Hungarici, v. 9, p. 244250.Google Scholar
Montandon, A.L., 1913, Nepidae et Belostomatidae, Descriptions de deux espèces nouvelles: Bulletin de la Société des Sciences de Bucarest-Roumanie, v. 22, p. 122125.Google Scholar
Muli, J.R., and Mavuti, K.M., 2001, The benthic macrofauna community of Kenyan waters of Lake Victoria: Hydrobiologia, v. 458, p. 8390.Google Scholar
Nel, A., and Paicheler, J.C., 1992, Les Heteroptera aquatiques fossiles, état actuel des connaissances (Heteroptera: Nepomorpha et Gerromorpha): Entomologica Gallica, v. 3, p. 159182.Google Scholar
Nel, A., and Waller, A., 2006, A giant water bug from the Lower Cretaceous Crato Formation of Brazil (Heteroptera: Belostomatidae: Lethocerinae): Zootaxa, v. 1220, p. 6368.Google Scholar
Olsen, P.E., 1979, A new aquatic eosuchian from the Newark Supergroup (Late Triassic–Early Jurassic) of North Carolina and Virginia: Postilla, v. 176, p. 114.Google Scholar
Olsen, P.E., Remington, C.L., Cornet, B., and Thomson, K.S., 1978, Cyclic change in Late Triassic lacustrine communities: Science, v. 201, p. 729733.Google Scholar
Orwa, P.O., Omondi, R., Ojwang, W., and Mwanchi, J., 2015, Diversity, composition and abundance of macroinvertebrates associated with water hyacinth mats in Lake Victoria, Kenya: African Journal of Environmental Science and Technology, v. 9, p. 202209.Google Scholar
Polhemus, J.T., 1995, Nomenclatural and synonymical notes on the genera Diplonychus Laporte and Appasus Amyot and Serville (Heteroptera: Belostomatidae): Proceedings of the Entomological Society of Washington, v. 97, p. 649–653.Google Scholar
Polhemus, J.T., 2000, North American Mesozoic aquatic Heteroptera (Insecta, Naucoroidea, Nepoidea) from the Todilto Formation, New Mexico, in Lucas, S.G., ed., New Mexico’s Fossil Record: New Mexico Museum of Natural History and Science, Bulletin 16. p. 2940.Google Scholar
Popov, Y.A., 1968, True bugs of the Jurassic Karatau fauna (Heteroptera), in Jurassic insects of Karatau, Bulletin of the Academy of Sciences of the USSR, Section of General Biology, Nauka Press, Moscow, p. 99113. [in Russian]Google Scholar
Popov, Y.A., 1971, Istoricheskoe razvitie poluzhestkokrylykh infraotryada Nepomorpha (Heteroptera) [Historical Development of True Bugs of the Infraorder Nepomorpha (Heteroptera)]: Trudy Paleontologicheskogo Instituta, Akademiya Nauk SSSR, v. 129, 230 p. [in Russian]Google Scholar
Popov, Y.A., 1989, New fossil Hemiptera (Heteroptera + Coleorrhyncha) from the Mesozoic of Mongolia: Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, v. 3, p. 166181.Google Scholar
Popov, Y.A., 1996, The first record of a fossil water bug from the Lower Jurassic of Poland (Heteroptera: Nepomorpha: Belostomatidae): Polskie Pismo Entomologiczne, v. 65, p. 101105.Google Scholar
Popov, Y.A., Dolling, W.R., and Whalley, P.E.S., 1994, British Upper Triassic and Lower Jurassic Heteroptera and Coleorrhyncha (Insecta: Hemiptera): Genus, International Journal of Invertebrate Taxonomy, v. 5, p. 307347.Google Scholar
Popov, Y.A., Rust, J., and Brauckmann, C., 2000, Insektenreste (Hemiptera: Belostomatidae; Coleoptera) aus dem Ober-Jura (“Kimmneridge”) von Nettelstedt (Wiehengebirge, NW-Deutschland) [Insect remains (Hemiptera: Belostomatidae; Coleoptera) from the Upper Jurassic (“Kimmeridgian”) of Nettelstedt (Wiehengebirge, NW Germany)]: Neues Jahrbuch für Geologie und Paläontologie-Monatshefte, v. 2, p. 8392.Google Scholar
Poschmann, M., Schindler, T., and Uhl, D., 2010, Fossil-Lagerstätte Enspel–a short review of current knowledge, the fossil association, and a bibliography: Palaeobiodiversity and Palaeoenvironments, v. 90, p. 320.Google Scholar
Prokop, J., and Nel, A., 2000, First record of the genus Lethocerus Mayr, 1853, from the Lower Miocene of the Most Formation in northern Bohemia, Czech Republic (Heteroptera, Belostomatidae): Bulletin de la Société entomologique de France, v. 105, p. 491495.Google Scholar
Richardson, G., Ward, C.R., and Huddleston, E.W., 1972, Aquatic Macroinvertebrates of the Playa: U.S. International Biological Program, Desert Biome, Logan, UT, RM, v. 72–53, p. 2.2.2.4-702.2.2.4-95.Google Scholar
Riek, E.F., 1974, Upper Triassic insects from the Molteno “Formation”, South Africa: Palaeontology of Africa, v. 17, p. 1931.Google Scholar
Říha, P., and Kukalová, J., 1967, Eine neue tertiäre Wasserwanze aus dem Bechlejovicer Diatomit (Heteroptera, Belostomatidae): Acta Entomologica Bohemoslovaca, v. 64, p. 259260.Google Scholar
Rust, J., and Ansorge, J., 1996, Bemerkenswerte Moler-Insekten: Fossilien, v. 1996, p. 359364.Google Scholar
Say, T., 1832, Descriptions of new species of Heteropterous Hemiptera of North America: New Harmony, Indiana, 39 p. [p. 1–4 issued 1831]Google Scholar
Scheibler, E.E., and Ciocco, N.F., 2013, Diversity of aquatic insects and other associated macroinvertebrates in an arid wetland (Mendoza Province, Argentina): Revista De La Sociedad Entomologica Argentina, v. 72, p. 4153.Google Scholar
Schuh, R.T., and Slater, J.A., 1995, True Bugs of the World (Hemiptera: Heteroptera): Classification and Natural History: New York, Cornell University Press, 336 p.Google Scholar
Scott, J., 1874, On a collection of Hemiptera Heteroptera from Japan. Descriptions of various new genera and species: Annual Magazine of Natural History, Series 4, v. 14, p. 289452.Google Scholar
Shcherbakov, D.E., 2010, The earliest true bugs and aphids from the Middle Triassic of France (Hemiptera): Russian Entomological Journal, v. 19, p. 179182.CrossRefGoogle Scholar
Shcherbakov, D.E., Lukashevich, E.D., and Blagoderov, V.A., 1995, Triassic Diptera and initial radiation of the order: International Journal of Dipterological Research, v. 6, p. 75115.Google Scholar
Siddiqi, S.Z., 2008, Limnological profile of high-impact meteor crater Lake Lonar, Buldana, Maharashtra, India, an extreme hyperalkaline, saline habitat, in Sengupta, M., and Dalwani, R., ed., Proceedings of Taal 2007: The 12th World Lake Conference, p. 1597–1613.Google Scholar
Smith, R.L., 1997, Evolution of paternal care in the giant water bugs (Heteroptera: Belostomatidae) in Choe, J.C., and Crespi, B.J., The Evolution of Social Behavior in Insects and Arachnids: New York, Cambridge University Press, p. 116149.CrossRefGoogle Scholar
Spinola, M., 1850, Tavola sinottica dei generi spettanti alla classe de gli insetti arthrodignati Hemiptera Linn., Latr., Rhyngota Fabr., Rhynchota Burm. Modena, 60 p. [Republished 1852, Memorie di matematica e di fisica della Societá italiana delle Scienze Modena, v. 25, p. 43100.]Google Scholar
Stål, C., 1855, Nya Hemiptera. Öfversigt af Kongl: Vetenskaps-Akademiens Förhandlingar, v. 11, p. 231255.Google Scholar
Stål, C., 1861, Nova methodus familias quasdam Hemipterorum disponendi: Öfversigt af Kongliga Vetenskaps-Akademiens Förhandlingar, v. 18, p. 195212.Google Scholar
Stål, C., 1862, Hemiptera Mexicana enumeravit species-que novas descripsit: Stettin Entomologische Zeitung Herausgegeben von dem Entomologischen Vereine zu Stettin, v. 23, 461 p.Google Scholar
Takhelmayum, K., and Gupta, S., 2011, Distribution of aquatic insects in phumdis (floating island) of Loktak Lake, Manipur, northeastern India: Journal of Threatened Taxa, v. 3, p. 18561861.Google Scholar
Tasch, P., 1969, Branchiopoda, in Moore, R.C., ed., Treatise on Invertebrate Paleontology, Pt. R, Arthropoda, v. 4: Boulder, Colorado and Lawrence, Kansas, Geological Society of America, Inc. and University of Kansas Press, p. R128R191.Google Scholar
Tobler, M., Schlupp, I., and Plath, M., 2007, Predation of a cave fish (Poecilia mexicana, Poeciliidae) by a giant water-bug (Belostoma, Belostomatidae) in a Mexican sulphur cave: Ecological Entomology, v. 32, p. 492495.Google Scholar
van de Kamp, P.C., and Leake, B.E., 1996, Petrology, geochemistry, and Na metasomatism of Triassic-Jurassic non-marine clastic sediments in the Newark, Hartford, and Deerfield rift basins, northeastern USA: Chemical Geology, v. 133, p. 89124.Google Scholar
Vega, F.J., García-Barrera, P., Perrilliat, M.D.C., Coutiño, M.A., and Mariño-Pérez, R., 2006, El Espinal, a new plattenkalk facies locality from the Lower Cretaceous Sierra Madre Formation, Chiapas, southeastern Mexico: Revista Mexicana de Ciencias Geológicas, v. 23, p. 323333.Google Scholar
Voelker, V.J., 1968, Untersuchungen zu Ernährung, Fortpflanzungsbiologie und Entwicklung von Limnogeton fieberi Mayr (Belostomatidae, Hemiptera) als Beitrag zur Kenntnis von natürlichen Feinden tropischer Süßwasserschnecken: Entomologische Mitteilungen asu dem Zoologischen Staatsinstitut u. Zoologischen Museum Hamburg, v. 3, p. 124.Google Scholar
Wedmann, S., 2000, Die Insekten der oberoligozänen Fossillagerstätte Enspel (Westerwald, Deutschland): Systematik, Biostratonomie und Paläoökologie: Mainzer Naturwissenschaftliches Archiv, v. 23, 154 p.Google Scholar
Yannawar, V.B., and Bhosle, A.B., 2013, Cultural Eutrophication of Lonar Lake, Maharashtra, India: International Journal of Innovation and Applied Studies, v. 3, p. 504510.Google Scholar
Zamboni, J.C., 2001, Contribution to the knowledge of the aquatic paleoentomofauna from Santana Formation (Araripe Basin, Lower Cretaceous, northeast Brazil) with description of new taxa: Acta Geologica Leopoldensia, v. 24, p. 129135.Google Scholar
Zhang, J., 1989, Fossil Insects from Shanwang, Shandong, China: Jinan, China, Shandong Science and Technology Publishing House, 459 p. [in Chinese with English summary]Google Scholar
Zhang, J.S.B., and Zhang, X., 1994, Miocene Insects and Spiders from Shanwang, Shandong: Beijing, China, Science Press, 298 p. [in Chinese with English summary]Google Scholar
Figure 0

Table 1 List of fossil belostomatid species.

Figure 1

Figure 1 Triassonepa solensis n. gen. n. sp., habitus of holotype, VMNH 94671. Scale bar is 2 mm.

Figure 2

Figure 2 Photographs of adult specimens of Triassonepa solensis n. gen. n. sp.: (1) VMNH 49641; (2) VMNH 53881; (3) VMNH 53880; (4) VMNH 94672. Scale bars are 2 mm.

Figure 3

Figure 3 Reconstruction of Triassonepa solensis n. gen. n. sp. showing major morphological characters.

Figure 4

Figure 4 Morphological comparison of the forelegs, hemelytra, metathoracic legs, and terminalia of adult Triassonepa solensis n. gen. n. sp. and extant belostomatid species: (1) foreleg, VMNH 94671, holotype; (2) foreleg, Belostoma flumineum Say, 1832; (3) foreleg, Benacus griseus (Say, 1832) (formerly genus Lethocerus); (4) hemelytra, VMNH 53881; (5) hemelytra, Diplonychus urinator sudanensis Linnavuori, 1971; (6) setal fringe on metathoracic leg, VMNH 50230; (7) setal fringe on metathoracic leg, Belostoma elongatum Montandon, 1908; (8) double setal fringe on metathoracic leg, VMNH 90281; (9) double setal fringe on metathoracic leg, VMNH 90279; (10) metathoracic leg, VMNH 94671, holotype; (11) female terminalia, VMNH 90281; (12) male terminalia, VMNH 94671, holotype; (13) terminalia, Diplonychus urinator sudanensis Linnavuori, 1971. Scale bars are 1 mm.

Figure 5

Figure 5 Triassonepa solensis n. gen. n. sp. growth series: (1) Instar I, VMNH 94575a; (2) Instar II, VMNH 50512; (3) Instar III, VMNH 53871; (4) Instar IV, VMNH 54155; (5) Instar V, VMNH 52498. Scale bar is 2 mm, located in photo 1.

Figure 6

Figure 6 Lengths of Triassonepa solensis n. gen. n. sp. instars and adults: 70 specimens (51 nymphs, 19 adults) were measured. The two largest adult specimens are males.

Figure 7

Table 2 Mean lengths (in mm) of the five instars of Triassonepa solensis n. gen. n. sp. (this study), Lethocerus maximus (Cullen, 1969), L. mazzai (De Carlo, 1962), Hydrocyrius columbiae (Miller, 1961), Belostoma flumineum (Flosi, 1980), B. malkini (Cullen, 1969), and Abedus breviceps (Keffer and McPherson, 1988).

Figure 8

Table 3 Growth ratios Triassonepa solensis n. gen. n. sp. (this study), Lethocerus maximus (Cullen, 1969), L. mazzai (De Carlo, 1962), Hydrocyrius columbiae (Miller, 1961), Belostoma flumineum (Flosi, 1980), B. malkini (Cullen, 1969), and Abedus breviceps (Keffer and McPherson, 1988) (the same species as in Table 2), calculated by dividing instar length by length of the previous instar.