Natatory Setae Research Articles

Underestimated diversity and range size of diving beetles in tank bromeliads—Coleoptera of ‘hygrofloric’ lifestyle (Dytiscidae)

Abstract Tank bromeliads provide a vast amount of stagnant water high up in the Neotropical forest canopy. However, the aquatic macroinvertebrate diversity in this specialized habitat remains poorly explored. Here, we study obligatorily bromeliadicolous species of the diving beetle genus Copelatus Erichson, 1832. We review the known species Copelatus bromeliarum Scott, 1912 (Trinidad and Venezuela) and Copelatus bimaculatus Resende & Vanin, 1991 (Brazil). We describe three new species: Copelatus espinhasso sp. nov. (Brazil), Copelatus florae sp. nov. (Brazil, Colombia, Costa Rica, Ecuador and Panama) including its larva, and Copelatus panguana sp. nov. (Peru). Based on their male genital morphology, these species form a distinct clade within the genus. Other shared characters such as compact drop-shaped habitus, shortened appendages, and reduction of natatory setae on legs are interpreted as adaptations for what we call the ‘hygrofloric’ lifestyle. We document the thin water layer between leaf axils as the preferred habitat of both Copelatus adults and larvae, and not necessarily the central tank.

On Caledromusrobinsmithi, a new genus and species of Psychrodromini Martens, 2001 (Crustacea, Ostracoda, Herpetocypridinae) from New Caledonia (Pacific Ocean).

The New Caledonian Archipelago is a hot spot for biodiversity and endemism. Whereas popular groups such as birds and plants are well-studied, invertebrate groups such as ostracods remain ill-known. Here, Caledromusrobinsmithigen. et sp. nov. is described from a single locality on 'Grande Terre', the main island of the archipelago. The new genus belongs to the Psychrodromini, one of the four tribes in the subfamily Herpetocypridinae (family Cyprididae). Caledromusgen. nov. can be distinguished from all other herpetocypridinids by a combination of the following factors: the absence of marginal septa in both valves, the mildly developed marginal valve structures, the small Rome organ on the A1, the total reduction of the five natatory setae on the A2, the rectangular second palp segment of the Mx1, the broad and asymmetrical palp on the female T1, the absence of additional postlabyrinthal coils in the Hp and the seta Sp of the CR which is a fixed spine. Because of the close similarity to the genus Psychrodromus, the new genus is thought to have Palaearctic affinities, contrary to other ostracod species in New Caledonia, which are either circumtropical or with Australian zoogeographical connections.

Seven new species and two new genera of Physocypria sensu latu (Crustacea, Ostracoda) from Brazilian floodplains

We describe seven new species in two new genera of the Physocypria sensu latu clade (Cyclocypridinae) from three of the main Brazilian floodplains. Brasilocypria pea gen. et spec. nov. and Brasilocypria ricardopintoi gen. et spec. nov. occur in the Upper Paraná River floodplain and the South Matogrossense Pantanal, Claudecypria mesquitai gen. et spec. nov., Brasilocypria alisonae gen. et spec. nov. and Claudecypria rochei gen. et spec. nov. were found in the South Matogrossense Pantanal, and Brasilocypria lordi gen. et spec. nov. and Brasilocypria namiotkoi gen. et spec. nov. occur in the Amazon River floodplain. All new species here described were found as sexual populations. Generally, they have a short and suboval carapace, with the left valve overlapping the right valve on all sides, except for the dorsal side in some species. The morphology of the hemipenis and the prehensile palps, together with the shape of the valves, were the most important characters to distinguish the species. Size differences between species can be substantial. Several characters, such as the absence in all new species of the short accompanying seta of the five natatory setae on the antenna; the presence in all new species of a long seta next to the two a-setae on the first thoracopod, and the presence/absence or differences in length of specific setae on the second and third thoracopod, are relevant for the generic diagnoses. We also redefine Keysercypria Karanovic, 2011.

Larval morphology of the Neotropical diving beetle genus Hemibidessus Zimmermann, 1921 (Coleoptera: Dytiscidae: Bidessini).

We describe for the first time the larva of the diving-beetle genus Hemibidessus Zimmermann, 1921, based on instars II and III of H. conicus (Zimmermann, 1921). We include detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi in order to discover useful characters for distinguishing Hemibidessus larvae from those of other known Bidessini. Hemibidessus larvae characteristically have elongate legs armed with natatory setae and elongate urogomphi that bear numerous secondary setae, features commonly associated with an increased swimming ability. These characters are shared with Brachyvatus Zimmermann, 1921, suggesting a close phylogenetic relationship between these two genera. The primary seta UR8 is inserted apically on urogomphomere 2 in Hemibidessus larvae, a feature so far only shared with the mature larva of Yola Gozis, 1886. Other characters that combined with those previously mentioned are useful to distinguish Hemibidessus from other bidessines are the absence of a ventroapical spinula on antennomere 3 and the presence of secondary dorsal setae on protarsus.

Redescription of the monotypic micro-predatory isopod genera Alitropus H. Milne Edwards, 1840 and Barybrotes Schioedte & Meinert, 1879 (Isopoda, Cymothoida), with a taxonomic key to the Cymothooidea Leach, 1814 from India

ABSTRACT The two monotypic genera of micropredatory cymothoid isopods, Alitropus H. Milne Edwards, 1840 (Aegidae White, 1850) and Barybrotes Schioedte and Meinert, 1879 (Barybrotidae Hansen, 1890), are revised and their species redescribed from India. Alitropus typus is distinguished by its slender and elongate body, broadly triangular cephalon with the antero-median margin slightly produced, mandible palp longer than mandible and peduncle of uropod long. Barybrotes indus Schioedte and Meinert, 1879 is redescribed based on the type and additional material from Indian waters. Barybrotes indus is distinguished by its elongated body, large eyes, antero-median rostrum which separates the bases of the antennae, long natatory setae on the pereopods and all seven pairs by dilatation of the joints or garniture of setae are auxiliary to swimming. A key to the Indian family of the superfamily Cymothooidea Leach, 1814 is presented.

The megalopal stage of the hydrothermal vent crab Austinograea rodriguezensis Tsuchida amp; Hashimoto, 2002 (Decapoda: Bythograeidae): a morphological description based on CLSM images.

The Bythograeidae is unique amongst brachyuran crab taxa as it is the only family where all 6 genera and 16 species are endemic to hydrothermal vents. During the research conducted by German Federal Institute for Geosciences and Natural Resources to identify inactive polymetallic sulphide deposits along Central and Southeast Indian Ridges, the INDEX project collected from hydrothermal vent fields 6 Bythograeidae megalopae. Entire specimens and dissected appendages were stained, mounted on slides and examined using Light Microscopy and Confocal Laser Scanning Microscopy. Additional molecular analysis using mtCOI confirmed the identification of the specimens as Austinograea rodriguezensis Tsuchida Hashimoto, 2002. The megalopal stage of A. rodriguezensis shows similarities and distinctions between the characters of two other bythograeid megalopae, Bythograea thermydron Williams, 1980, and B. microps Saint Laurent, 1984. Unlike other brachyuran megalopae, B. thermydron and A. rodriguezensis lack long serrate setae and stout serrate spines on the dactylus of the fifth pereiopod. In both species no coxal spines on the pereiopods were observed. The elliptical carapace of B. thermydron is broader than long vs longitudinally rectangular in A. rodriguezensis. This carapace shape resembles B. microps more than B. thermydron, however, the dorsal surface of B. microps carapace is densely covered in short setae vs only covered with short setae on the anterior 1/4 and the posterior 1/6 length of carapace in A. rodriguezensis. Furthermore, the amount of plumose natatory setae on the pleopods in B. microps is in total larger and more variable, than in A. rodriguezensis. Bythograeid megalopae seem quite generalized and miss specific features that reveal them distinctively as endemic vent crab. A distinction from other species is possible by observing the unique combinations of certain characters. This is the first megalopal stage description of Austinograea and the fourth within the Bythograeidae.

Description of the mature larva of four species of the Australasian endemic genus Sternopriscus Sharp, 1882 (Coleoptera: Dytiscidae) with phylogenetic considerations

The instar III larvae of the Australian endemic species Sternopriscus alpinus Hendrich and Watts, 2004, S. clavatus Sharp, 1882, S. hansardii (Clark, 1862) and S. multimaculatus (Clark, 1862) are described and illustrated for the first time. We explore implications for understanding the evolution of larval morphological traits amongst selected Sternopriscina genera. A parsimony analysis based on 84 larval characteristics of 11 species in six genera was conducted using the program TNT. Larvae of Sternopriscus Sharp, 1882 are characterised by the last abdominal segment not extending into siphon and by very elongate urogomphi. Sternopriscus is subdivided into two groups based either on absence or reduction in number of natatory setae along the dorsal margin of femora, tibiae and tarsi. Sternopriscus is postulated to be sister to a clade comprised of Chostonectes Sharp, 1882, Megaporus Brinck, 1943 and Antiporus Sharp, 1882.

Hydroporus novacula sp. n. from Georgia (Caucasus) (Coleoptera, Dytiscidae, Hydroporini)-the first terrestrial species of the genus?

Hydroporus novacula sp. n. is described on a single male accidentally found when collecting Staphylinidae (Coleoptera) in south-western Georgia (Caucasus) by sifting more or less dry material quite far from any water. The species belongs to the longulus-group of the genus (former subgenus Sternoporus). However, the shape of the median lobe, the club-like pro- and mesotibiae and the evenly curved protarsal claws separate it from all other species of the group. Additionally, no natatory setae could be detected on any leg of the single male studied. Together with the collecting circumstances, it appears not unlikely that the new species is the first terrestrial Hydroporus known to science. The species is described in detail and important features are illustrated.

A description of Ucides occidentalis Ortmann, 1897 (Crustacea : Decapoda : Ocypodidae) zoea I.

ABSTRACTIn order to facilitate the ecological study of the economically important red mangrove crab Ucides occidentalis, we describe the zoea I phase using samples hatched from gravid females taken from the Guayas River Estuary of Ecuador. No other phases of this species’ larval development have been described. The morphological differences between this developmental phase in U. occidentalis and its single congener U. cordatus that may be diagnostic include the number of segments in the pleon, the setation pattern of the basial endopodite of the maxillule, and, in maxillipeds I and II, the segmentation of the terminal plumose natatory setae.

Larval morphology of the Australian radiation Sternopriscina (Coleoptera: Dytiscidae, Hydroporinae): description and phylogenetic placement of the genus Chostonectes Sharp, 1882

The larvae of the Australian endemic species Chostonectes gigas (Boheman, 1858) and C. johnsonii (Clark, 1862) are described and illustrated for the first time, with detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. A parsimony analysis based on 83 informative larval characteristics of six species in four genera of the subtribe Sternopriscina was conducted using the program TNT. The monophyletic origin of the four Sternopriscina studied was strongly supported. Members of Paroster Sharp, 1882 characterise by the presence of three labial palpomeres, a unique feature within the subfamily Hydroporinae. Larvae of Barretthydrus Lea, 1927, Antiporus Sharp, 1882 and Chostonectes Sharp, 1882 evolved the presence of natatory setae on femora, tibia and tarsi. At the moment, Chostonectes is postulated to be closely related phylogenetically to Antiporus in the context of this study.

Description of the second- and third instar larvae of Platynectes (s. str.) decemnotatus (Aubé, 1838) (Coleoptera: Dytiscidae: Agabinae: Platynectini).

The second- and third instar larvae of Platynectes (s. str.) decemnotatus (Aubé, 1838) are described and illustrated in detail for the first time, with special emphasis on morphometry and chaetotaxy. Larvae of P. decemnotatus can be distinguished from most other Agabinae by having secondary setae on the urogomphus and share with the other known species described in detail the presence of a ventroapical spinula on antennomere 3 and the absence of an occipital suture, natatory dorsal setae on tibia and tarsus and natatory setae on urogomphus. Platynectes decemnotatus larvae differ from larvae of Agabus Leach, 1817, Hydrotrupes Sharp, 1882 (currently in Hydrotrupini), Ilybiosoma Crotch, 1873, Ilybius Erichson, 1832 and the previously described Platynectes species in having a one-segmented urogomphus, a character previously observed only in larvae of Agabinus Crotch, 1873. The second- and third instar larvae of P. decemnotatus differ from those of P. (Agametrus) curtulus (Régimbart, 1899) in having the apical lateroventral process of antennomere 3 protruding (not protruding in P. curtulus). The third-instar larva of P. decemnotatus can also be distinguished from that of P. (Gueorguievtes) decempunctatus (Fabricius, 1775) by the absence of secondary dorsal setae on the tibia.

Analysing morphological variation of appendages and labrum in 10 species of Heterocypris Claus, 1893 (Podocopida : Cyprididae) with additional description of Heterocypris exigua

Natural selection can lead to speciation, but its effects depend on amount of morphological variation within populations. In Ostracoda, the appendages enclosed within the calcified carapace are less influenced by environmental conditions in comparison with carapace valves. Here, we explored morphological variation of appendages and labrum in cosmopolitan genus Heterocypris, investigating the species occurring in Europe. With the aim to overcome taxonomical problems, both traditional and geometric morphometrics were applied. The relative lengths were analysed by one-way ANOVA and post-hoc tests to determine interspecific variation and sexual dimorphism. Significant traits were further analysed by Canonical Variate Analysis separately for males and females as segment width/length ratios and relative length of claws and setae ratios. Landmark-based geometric morphometrics were applied to analyse shape variation of the labrum and traits of the maxillular palp. From this, a new perspective on morphological variation within this genus emerged. Relative measurements of the second segment of the maxillular palp, and relative lengths of the natatory setae were found to be the characters that contribute most to discrimination among Heterocypris species. The most important discriminant traits in females are the relative lengths of the G2 and G1 claws. Heterocypris exigua is additionally described, as all findings demonstrated that this is the most distinctive species, the most similar to H. gevgelica. In conclusion, we found that in comparison with maxillular palp and other analysed characters, labrum traits showed as more reliable and deserve more attention in descriptions of new species.

Larval Morphology ofYolaGozis, 1886 (Coleoptera: Dytiscidae: Bidessini) and Comparison with other Genera of the Tribe Bidessini

The second and third instars of Yola wraniki Wewalka, 2004 are described and illustrated for the first time, with detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphi. The mature larva of Yola Gozis, 1886 can be distinguished from those of the other known Bidessini genera by the following combination of morphometric and chaetotaxic characters: ratio length of metathoracic leg/head width greater than 2.85; ratio length of urogomphus/head width greater than 2.70; absence of a ventroapical spinula on third antennomere; secondary temporal spine-like setae on parietale; natatory setae on tibia; secondary posteroventral setae on tarsus and secondary setae on urogomphus; presence of pore PAk and secondary dorsal setae on protarsus; and mandibular pore MNa located in a clearly distal position with respect to pore MNb. A key for the identification of the third instars of the genera of Bidessini known in detail is provided.

A new species of Afropinnotheres Manning, 1993 (Crustacea, Brachyura,Pinnotheridae) from southwestern India, the first record of the genus from the Indian Ocean, with a review of the Pinnotheridae of India and adjacent seas.

A new species of pinnotherid crab of the genus Afropinnotheres Manning, 1993, is described from the brown mussel, Perna perna (Linnaeus, 1758), in southwestern India. This is the first record of the genus from the western Indian Ocean, the other four species been recorded from the eastern Atlantic. The new species can be distinguished from all congeners in possessing a more rounded male carapace, form of the chela, relatively longer ambulatory legs which have no natatory setae, presence of dense pubescence on the male ambulatory legs, and the shape of the male and female telsons. The Indian Pinnotheridae is also reviewed and the taxonomy of the species reappraised. The taxonomy of Pinnaxodes Heller, 1865, and Holothuriophilus Nauck, 1880, is also discussed, in the context of their similarity to Afropinnotheres.

Description of the third instar of Hygrobia nigra (Clark, 1862)Coleoptera: Paelobiidae), with a key for the identification of mature larvae of Hygrobia Latreille, 1804 and phylogenetic analysis.

The mature larva of the squeak beetle Hygrobia nigra (Clark, 1862) (Paelobiidae) is studied for the first time based on detailed descriptions and illustrations of selected structures, with special emphasis on morphometry and chaetotaxy. A key for the identification of mature larvae of four of the six species of Hygrobia Latreille, 1804 known worldwide is presented. The phylogenetic relationships of the species are analyzed based on a cladistic analysis of a combined data set including larval and adult characters. Hygrobia nigra shares with the other known species of the genus several larval apomorphies including the presence of paramedian lip-like lobes on the epipharynx, a well-developed gula, gills on thoracic and first three abdominal sterna, and the maxillary stipites inserted into submental pouches, and is unique in the presence of a larger number of secondary setae on the metacoxa. The presence of a compact group of minute sensilla in the place where the galea is commonly located suggests that members of Hygrobia lost the galea, a condition independently evolved in some dytiscid lineages. The Australian species form a well-supported clade characterized by the presence of a short nasale, fewer natatory setae on the metatibia, and a marked shortening of the antennal sensorial appendage and the last abdominal segment. However, no larval characters were discovered to resolve relationships within that clade. The Palearctic H. hermanni (Fabricius, 1775) lacks a distinct nasale and is resolved as sister to the clade formed by the Australian species.

The Unknown Larva of the Minute Diving Beetle GenusBrachyvatusZimmermann, 1919 (Coleoptera: Dytiscidae: Bidessini)

The three larval instars of Brachyvatus acuminatus (Steinheil, 1869) (the type species of the bidessine genus Brachyvatus Zimmermann, 1919) are described and illustrated for the first time including detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. Larvae of this genus are characterized by the absence of the primary pore ABc, which is a synapomorphy of the tribe Bidessini. Brachyvatus larvae can be separated from those of all other known Bidessini genera by the following combination of characters: very small size; lateral branches of nasale well visible in dorsal view; ventroapical spinula on third antennomere absent; meso- and metatergite of instar I with anterotransverse carina; siphon short; long urogomphi with secondary setae; seta PA3 absent; setae UR2 and UR4 inserted contiguously; natatory setae present on tibiae in instars II–III.

Phylogenetic relationships, larval morphology, and chaetotaxy of the subfamily Coptotominae (Coleoptera: Dytiscidae)

AbstractLarval morphology of the monogeneric subfamily Coptotominae (Coleoptera: Dytiscidae) is described and illustrated in detail, with particular emphasis on morphometry and chaetotaxy. Larvae ofCoptotomusSay are unique within Dytiscidae in the presence of tracheal gills on the abdominal segments I–VI, a short bifid horn or nasale in instar I, long spinulae on the urogomphus in instar I, and rows of natatory setae on both the internal and external margins of the urogomphus in instars II and III. A cladistic analysis based on 125 larval characters sampled among representatives of other dytiscid subfamilies supports a sister-group relationship between Coptotominae and Laccophilinae based on the shared absence of setae LA10 and LA12 on the second labial palpomere and of pore ABc on the abdominal segment VIII. The clade Coptotominae + Laccophilinae resolved as sister to Lancetinae, all three subfamilies sharing the presence of an unusually low number of lamellae clypeales in the first instar (a condition called four-peg-pattern), postulated to have evolved secondarily within Dytiscidae.

Spanglerodessus shorti and Incomptodessus camachoi, new genera and species of Bidessini from Guyana and Venezuela (Coleoptera: Dytiscidae: Hydroporinae)

Two new genera and species are described. Spanglerodessus n. gen. is described to include the single new species, S. shorti n. sp. from localities in eastern Venezuela and western Guyana. This genus is similar to Bidessodes Régimbart and Fontidessus Miller and Spangler, but differs from the first in having overall dark coloration, lack of dorsal color patterns or iridescence, a broad lateral bead, and broad and robust habitus. From Fontidessus the genus differs in being much more robust and lacking natatory setae. Incomptodessus n. gen. is described to include a single new species I. camachoi n. sp. from localities in the upper Orinoco River basin in Amazonas and Bolivar States. This genus differs from similar bidessine genera, Sharphydrus Omer-Cooper, Tyndallhydrus Sharp, Liodessus Guignot and Neobidessus Young, in having impunctate metacoxae and metaventrite and lacking basal striae on the elytra.

Morphology and growth of the larval stages of Geograpsus lividus (Crustacea, Brachyura), with the descriptions of new larval characters for the Grapsidae and an undescribed setation pattern in extended developments

Cuesta, J.A., Guerao, G., Schubart, C.D. and Anger, K. 2011. Morphology and growth of the larval stages of Geograpsus lividus (Crustacea, Brachyura), with the descriptions of new larval characters for the Grapsidae and an undescribed setation pattern in extended developments. —Acta Zoologica (Stockholm) 92: 225–240. Among the eight currently recognized genera and 40 species belonging to the brachyuran crab family Grapsidae (Thoracotremata), the complete larval development is only known for three species of Metopograpsus. In this study, we investigated the larval development of Geograpsus lividus originating from Jamaica and reared under controlled conditions in the laboratory. It consists of eight zoeal stages and the megalopa, representing the longest recorded developmental pathway for any brachyuran. Although long developments had been suggested for some species, based on specimens collected from the plankton, these were never confirmed by laboratory culture. In this study, zoeal growth (measured as increase in body size, dry mass, and contents of carbon, nitrogen, and hydrogen) is quantified, and morphological and meristic characters of the larval stages of G. lividus are described and illustrated. The development from hatching to the end of the zoeal phase took 2 months. During this time span, larval size (cephalothorax length) increased 4.4-fold, while the various measures of biomass increased by factors of 57–72. Morphologically, the larvae present most characters previously established for the family Grapsidae. However, the two last zoeal stages show new features that differ from the typical setation pattern known from grapsid species with only five zoeal stages. These were found in the number of natatory setae on the exopods of the maxillipeds and in the setation of the basis of the first maxilliped. Other characters, which had previously only been described for zoeae of Pachygrapsus and plankton-collected ones attributed to Planes, were observed also in G. lividus and could be confirmed as common features for the Grapsidae. Moreover, the larvae of G. lividus present a spinulation on the lateral and rostral spines of the cephalothorax. This character is recorded for the first time in grapsid crabs. A comparison of these observations is made with those based on terminal zoeal stages of species belonging to other brachyuran families, where similar characters have been documented.

Descriptions of the Second and Third Instars ofHeterosternuta sulphuria(Matta and Wolfe) (Coleoptera: Dytiscidae: Hydroporinae), with A Key For Identification of the Known Larvae ofHeterosternutaStrand

Descriptions of structures of the second and third instars of Heterosternuta sulphuria (Matta and Wolfe) are presented. Larvae of H. sulphuria are fairly similar to the known larvae of Heterosternuta Strand, all of these being characterized by the presence of lateral spinulae on the prementum, the absence of natatory setae on the legs, the absence of spiracular openings on the mesothorax and abdominal segments 1–7, siphon of the third instar cone-shaped, short, and highly constricted posterior to insertion of urogomphi, and urogomphomere 1 with secondary setae. A key to identification of the third instars of known species of Heterosternuta is provided.