Hydrolutos piaroa Derka, Svitok & Fedor 2015

Derka, Tomáš, Svitok, Marek & Fedor, Peter, 2016, Hydrolutos piaroa sp. n. (Orthoptera: Anostostomatidae), a new semiaquatic Lutosini species from south-western Venezuelan lowland streams, Zootaxa 4066 (4), pp. 485-492 : 486-491

Hydrolutos piaroa Derka, Svitok & Fedor 2015

http://lsid.speciesfile.org/urn:lsid: Orthoptera .speciesfile.org:TaxonName:473461

Description. Male: Body dark brown. Head capsule, including mandibles, dark brown with bright pattern on vertex, eyes black with semicircular light bands posteriorly. Palpi entirely light. Thorax and abdomen very dark brown dorsally. Legs lighter than body.

Head. Antennal flagellum longer than total body length, proximally smooth, in middle and distal section suddenly (between antennal segment 40 and 50) covered by short fine microsetae. Fastigium proximally broader than antennal segment S1, slightly flattened, with 2 lateral bright spots, not declinate, with a median carina. Clypeus trapezoidal, with distinct bright median carina and bright pattern latero-distally. Labrum heart-shaped, proximally broader than distally, with indistinct median carina in its apical half. Maxillary palps bright, segment 4 (distal half) and 5 covered by short fine and soft microsetae. Eyes elevated in frontal view, with rear ommatidia light ( Fig. 2).

Thorax. Pronotum slightly elevated over mesonotum, slightly wider than long, bordered by a smooth rolled margin, containing both smooth and gently rugose areas. All thoracic sterna with 2 spines, prosternum with 2 indistinct spines posterolaterally elevated, mesosternum with 2 spines posterolaterally elevated, metasternum with 2 distinct spines posterolaterally elevated. Legs long, forecoxa with a moderate lateral spine, femora without spines. Fore tibiae dorsally with 1 spine medially and 2 apically, ventrally with 2 rows of 5 spines (including the apical ones). Middle tibiae dorsally with a row of 4 spines on internal side and a row of 3 spines on external side, ventrally with 2 rows of 5 spines. Hind tibiae dorsally with 2 lateral and 1 central combs of short but firm spines, 2 pairs of terminal spines, ventrally with 7 short spines, 2 moderate subterminal and 2 superior terminal spines. Tympanum ellipsoid, grey-brown.

Abdomen. Abdominal apex and genitalia as on Figures 3 , 4 , 5. Abdominal tergites smooth with tiny pointed scales and sporadic yellowish maculae. Genitalia pubescent. Supra-anal plate oval, with no emargination. Cerci cylindrical, rugose, directed gently upwards, incurved, with blunt apices and without internal processes. Subgenital plate almost twice longer than wide, rugose, posterior margin with V-shaped emargination, with long styli.

Measurements. Body length 38.1 mm (including cerci 41.2), fastigium width 1.5 mm, interocular space 7.0 mm, pronotum length 10.5 mm, width 12.4 mm, hind femur length 31.0, width 8.2 mm (max.), 2.5 mm (min.), hind tibia length 30.0 mm, hind tarsus length 13.3 mm, hind tarsalia length: I 3.0 mm, II 1.9 mm, III 1.8 mm, IV 1.5 mm, abdomen length (without cerci) 18.2 mm.

Female: Body dark brown. Head capsule, including mandibles, dark brown with bright pattern on vertex, eyes black with semicircular light bands posteriorly. Palpi completely light. Thorax and abdomen very dark brown dorsally. Legs lighter than body.

Head. Antennal flagellum longer than total body length, proximally smooth, in middle and distal section suddenly (between antennal segment 40 and 50) covered by short fine microsetae. Fastigium proximally more narrow than antennal segment S1, slightly flattened, with 2 lateral bright spots, not declinate, with a median carina. Clypeus trapezoidal, with distinct bright median carina and bright pattern latero-distally. Labrum heart-shaped, proximally broader than distally, with indistinct median carina in its apical half. Maxillary palps bright, segment 4 (distal half) and 5 covered by short fine and soft microsetae. Eyes elevated in frontal view, with rear ommatidia light ( Fig. 2).

Thorax. Pronotum slightly elevated over mesonotum, slightly wider than long, bordered by a smooth rolled margin, containing both smooth and gently rugose areas. All thoracic sterna with 2 spines, prosternum: 2 indistinct spines posterolaterally elevated, mesosternum: 2 spines posterolaterally elevated, metasternum: 2 distinct spines posterolaterally elevated. Legs long, forecoxa with a moderate lateral spine, femora without spines. Fore tibiae dorsally with 1 spine medially and 2 apically, ventrally with 2 rows of 5 spines (including the apical ones). Middle tibiae dorsally with a row of 4 spines on internal side and a row of 3 spines on external side, ventrally with 2 rows of 5 spines. Hind tibiae dorsally with 2 lateral and 1 central combs of short but firm spines, 2 pairs of terminal spines, ventrally with 7 short spines, 2 moderate subterminal and 2 superior terminal spines. Tympanum ellipsoid, grey- brown.

Abdomen. Abdominal apex and genitalia as on Figures 7 , 8 . Abdominal tergites smooth with tiny pointed scales and sporadic yellowish maculae. Ovipositor slightly dorsad curved with smooth dorsal and ventral margins. Cerci conical angustate distally, hirsute. Epiproct triangular acute. Subgenital plate triangular, longer than broad.

Measurements. Body length 38.0 mm (including ovipositor 53.3 mm), fastigium width 1.2 mm, interocular space 6.0 mm, antenna: damaged, pronotum length 10.1 mm, width 13.8 mm, hind femur length 34.2 mm, width (9.8 mm max.), (3.3 mm min.), hind tibia length 31.9 mm, hind tarsus length 15.0 mm, hind tarsalia length: I 3.6 mm, II 1.4 mm, III 1.2 mm, IV 1.4 mm, abdomen length (without ovipositor) 18.0 mm, ovipositor length 15.0 mm, cerci length 4.0 mm, subgenital plate length 3.6 mm.

Type data and depository. Holotype: 1 ♂ body length 27.5 mm, Venezuela, Edo. Amazonas, Tobogán de la Selva, 154 m a.s.l., 05°23′8.1″ N, 67°36′53.9″ W, 1.XII. 2011. Holotype has been preserved in alcohol. paratype: 1 ♀, Venezuela, Edo. Amazonas, Tobogán de la Selva, 154 m a.s.l., 05°23′8.1″ N, 67°36′53.9″ W, 1.XII. 2011. Allotype has been preserved in alcohol.

Holotype and allotype will be deposited in Museo del Instituto de Zoología Agrícola ( MIZA), Facultad de Agronomía, Universidad Central de Venezuela, Maracay, Edo. Aragua, Venezuela.

Etymology. Species named after Piaroa Amerindians, the original inhabitants of the region of the type locality.

Diagnosis. The species is easily distinguished by a few characters. Posterior margin of the male subgenital plate with V-shaped emargination, which is the unique character among the known Hydrolutos species. Male subgenital plate almost 2 times longer than wide, but as long as wide in H. roraimae , H. chimantea , H. aracamuni and H. breweri and longer than wide in H. gransabanensis . Posterior margin of epiproct oval like in H. aracamuni , while strongly bilobulate in H. gransabanensis , s lightly bilobulate in ( H. Auyan as well as H. breweri ) and very slightly bilobulate in H. chimantea . Female subgenital plate triangular, longer than wide (like in H. aracamuni ), but not triangular in the remaining species. Maxillary palps light-colored, segment 4 (distal half) and 5 covered by short, fine and soft microsetae, but dark with few microsetae in H. aracamuni . Hind femur 1.7-1.9 times larger than abdomen, while in H. aracamuni hind femur only slightly larger than abdomen.

Ecology. As the other members of the genus, H. piaroa is considered a semiaquatic species, being able to breathe, walk and swim in aquatic habitats. It is active at night when it leaves crevices in river banks and behind waterfalls where it spends the daylight hours. H. piaroa was the only known Hydrolutos species inhabiting lowland streams, while the other species are recorded at higher altitudes (usually summits of tepuis). However, the type locality is not a standard lowland water body; on the contrary it forms a turbulent stream cascading among granitic boulders, surrounded by dense tropical forests.

Figures

FIGURE 3. Genitalia of male Hydrolutos piaroa— a ventral view.

FIGURE 4. Genitalia of male Hydrolutos piaroa— a dorsal view.

FIGURE 7. Genitalia of female Hydrolutos piaroa— a dorsal view.

FIGURE 8. Genitalia of female Hydrolutos piaroa— a lateral view.