Vietelmis jablonskii, Kodada, Ján, Sangpradub, Narumon, Somnark, Rungnapa, Gruľa, Daniel, Žiak, Dávid & Freitag, Hendrik, 2017

Kodada, Ján, Sangpradub, Narumon, Somnark, Rungnapa, Gruľa, Daniel, Žiak, Dávid & Freitag, Hendrik, 2017, Vietelmis jablonskii, a new species of riffle beetle from Laos and Thailand and new faunistic records on Vietelmis Delève, 1968 from Malaysia (Coleoptera: Elmidae), Zootaxa 4268 (1), pp. 131-140 : 132-138

Vietelmis jablonskii sp.nov.

( Figs 1, 2 , 7 , 11 , 17–19 )

Type locality ( Fig. 1 ). Stream ca. 6 m wide, shallow, meandering, with gravel in the stream beds; tributary of the Nam Song river near Nassom village, ca. 10 km from Vang Vieng village, 18°56'13''N, 102°21'50''E , 272 m a.s.l., Luang Prabang Province, Laos .

Material examined. Holotype ♂ ( NMW): “ Tributary of the Nam Song river near Nassom village, ca. 10 km from Vang Vieng village, 18°56'13'' N 102°21'50''E 272 m a.s.l., Luang Prabang Province, Laos, 18. 11. 2011 ”.

Paratype 1 ♂ ( KKU): “ Yakruae Creek , a second-order stream in Nam Nao National Park, ca. 50 m from the Visitors’Center, 16°44'20"N 101 º 34 ' 26" E, 840 m. a.s.l., Phetchabun Province, Thailand, 16. 12. 2013 ”.

Diagnosis. V. jablonskii sp. nov. is a moderately large species with: densely and finely punctate to nearly reticulate pronotum, moderately raised pronotal gibbosities, long carinae of sublateral pronotal gibbosities extending along posterior 0.55 of pronotal length, slightly raised and granulate elytral intervals 5, 7 and 8. The new species most resembles V. brevicornis and V. kovaci Kodada & Čiampor, 2000 in the general appearance ( Figs 8, 9 ). Within the genus, V. jablonskii sp.nov. is characterised by the following features: (1) parameres very strongly narrowed in apical third, acuminate, with long and conspicuous setae; (2) penis strongly and abruptly narrowed apically with tip acuminate; (3) metatibia with strong tibial spur; (4) claws of forelegs short, one quarter as long as terminal tarsomere.

Description of holotype. Habitus ( Fig. 7 ). Body elongate, 2.31 times as long as wide (BL/EW). Length (BL): 1.76 mm, width (EW): 0.76 mm. Coloration brown with pronotum slightly darker, femora and tibiae paler, cranium nearly black, antennae and tarsi reddish-brown.

Head. Clypeus about 3.1 times as wide as long; anterior margin feebly convex; surface reticulate and granulate, with short setae; granules distinctly smaller than facets, irregularly spaced. Frontoclypeal suture hardly discernible. Frons moderately declined, with plastron and granules; granules about one quarter as coarse as a facet size, smaller anteriorly than posteriorly, nearly regularly spaced. Antennal insertions separated by distance nearly equal to width of labrum. Eyes large, moderately protuberant, separated by a distance of 0.20 mm, nearly round in lateral view.

Thorax. Pronotum ( Fig. 11 ) slightly wider than long (MPW/PL: 1.18), broadest across posterior 0.4; lateral margins indistinctly crenate and very narrowly explanate; lateral sides slightly arcuate in posterior 0.4, more strongly arcuate in anterior 0.6; anterior margin sinuate; anterior angles slightly produced anteriad; anterolateral portion declined. Median sulcus deep and long, beginning at anterior fifth of pronotal length and reaching posterior margin, with bottom very densely and finely punctate. Sublateral gibbosities slightly convex, each with a distinct longitudinal carina beginning slightly before middle of pronotum; pronotal surface densely, finely punctate to nearly reticulate except for small sparsely punctate anterior and posterior areas; APW: 0.39 mm; PPW: 0.58 mm; MPW: 0.60 mm; PL: 0.51 mm. Anterior portion of prosternum at midline as long as prosternal process, finely punctate and nearly wrinkled medially; prosternal process longer than wide, nearly triangular, densely punctate/ microreticulate, anterior portion raised at middle. Metaventrite ca. 1.4 times as long as length of pronotum in front of coxae; disc depressed, surface microreticulate, with a few shallow coarse punctures; discrimen slightly raised; transverse groove absent; metaventral process wide, strongly raised and microreticulate on sides, smooth and declined on median portion. Scutellum flat, subtriangular, longer than wide; surface scarcely punctate, shiny. Elytra subparallel between anterior 0.10 and 0.65, then gradually convergent posteriorly; 1.65 times as long as wide, 2.45 times as long as pronotum; sides serrate, teeth smaller anteriorly and posteriorly; elytral apices nearly meeting at suture, but not conjointly rounded; elytra moderately convex in lateral view, with highest point at 0.55; EL: 1.26 mm, EW: 0.76 mm. Elytron with eight rows of punctures; punctures round, coarse and deeply impressed anteriorly, smaller and shallower posteriorly; rows 1–3 with coarse punctures along anterior 0.4, row 4 along anterior 0.6, row 5 and 6 along anterior 0.7, row 7 and 8 around 0.5. Intervals wider than rows; intervals 5, 7 and 8 slightly raised and granulate; granules closely arranged, interval 8 with granules smaller and more widely spaced than those on the preceding intervals; surface of remaining intervals punctate, punctures fine, sparse and setigerous, interstices smooth. Protibia moderately longer than pronotum, thickened close to distal portion, almost straight, mesal face with fringe of yellowish setae along distal 0.7. Mesotibia straight, distinctly longer than pronotum, mesal face with fringe of yellowish setae along distal 0.7. Metatibia moderately longer than mesotibia, widest near middle, curved at distal portion, with long distal spur; mesial surface with numerous small denticles at distal third. Tarsi slightly shorter than tibiae, tarsomeres 5 shorter than combined length of preceding segments; claws of foreleg short, one quarter as long as terminal tarsomere, moderately curved, other claws ca. 0.4 times as long as terminal tarsomere.

Abdomen. Ventrites with plastron and very small scattered granules; median portion of ventrite 1 without plastron, finely and very sparsely punctate, shiny; admedian carinae moderately raised, reaching posterior margin of ventrite; posterior angles of ventrite 2 slightly produced posterolaterad; lateral portion of ventrites 3 and 4 distinctly projecting posterolaterad; ventrite 5 granulate on sides, apex truncate; posteromesal keel of ventrite 5 raised, short and with numerous granules.

Aedeagus ( Fig. 17 ). Length 0.84 mm, phallobase 0.35 mm long, cylindrical. Penis very strongly narrowed apically with apex narrow, acuminate, apical portion not curved ventrally. Parameres nearly reaching tip of penis, 1.54 times as long as phallobase, strongly narrowed in apical 0.4, with numerous long setae on apical 0.3, separated along distal 0.6, flattened on apical portion; apices acuminate, feebly curved ventrally. Membranous ventral sac developed in distal half of penis. Male sternite VIII ( Fig. 18 ) with a few long setae near posterior margin, median strut 0.37 mm long; pregenital segments ( Fig 19 ) with posterior portion of sternite IX 1.98 times as long as anterior median strut.

Etymology. The species is named according to Daniel Jablonski from the Department of Zoology, Comenius University in Bratislava. Daniel is an excellent herpetologist, photographer, great explorer and adventurist travelling across the world.

Variability. The paratype of the new species varies slightly from the holotype in the following characters: 1) generally black colour (probably an older specimen) with dark brown femora and tibiae, antennae and tarsi reddishbrown; 2) body and elytra slightly larger: BL: 1.91 mm, EL: 1.35 mm; 3) elytral apices not meeting at suture; 4) punctures of elytral rows 1–5 moderately larger; 5) punctures on pronotal surface less densely arranged, so the surface appears to be more shiny. Due to the overwhelming similarity in all other characters examined, and almost to the exact match of their aedeagus: both specimens show the same unusual shape and proportions of the aedeagus with conspicuous and exceptional setation of the parameres, we consider the two specimens conspecific. This is also supported by the relatively short distance of ca. 280 km between the two collection sites, which are both tributaries of the Mekong River system.

Habitat. The holotype was collected in a shallow, meandering tributary stream of the Nam Song River near Nassom village ( Fig. 1 ); sampling was performed in gravel substrate. The paratype specimen from Thailand was collected from the Yakruae Creek ( Fig. 2 ), a second-order unpolluted and shaded stream, ca. 3‒5 m wide, and surrounded by secondary forest. Yakruae Creek has a heterogeneous channel morphology with cobble and gravel deposits, blank bedrock, as well as decaying leaf litter deposits. In general it flows only moderately fast, with slow pool sections, interrupted by riffles and run sections with distinctly higher current velocity. The specimen was retrieved from bottom gravel in a run section ca. 50 m from the Visitor’s Center of Nam Nao National Park.

Collecting remarks. In Thailand, Vietelmis jablonskii sp.nov. was collected by using a D-frame dip net to sample the gravel sediments described above (for details on the collection method, see Freitag 2015). Although samples were collected monthly, only a single male specimen was found. The species obviously occurs in low densities and is probably rare.

Distribution. So far known only from two localities, one in Laos and one in Thailand.

Figures

FIGURES 1 – 6. Localities of Uietelmis species: 1) the type locality of Uietelmis jablonskii sp. nov.: tributary of the Nam Song river near Nassom village, Luang Prabang Province, Laos; 2) the second locality of U. jablonskii: Yakruae Creek in the Nam Nao National Park, Phetchabun Province, Thailand; 3) habitat of U. kovaci: the Endau River in Endau-Rompin Park, Johor, Malaysia; 4) the type locality of U. lantiri, U. dentipes and U. ketua: the Sabalangang River, tributary of the Sapulut River, Sabah, Malaysia; 5) a rather atypical habitat of U. ketua and U. dentipes: a rivulet near Batu Punggul Resort in dense primary forest, Sabah, Malaysia; 6) an another habitat of U. ketua: a shaded stream in primary forest, tributary of the Kuamut River near Kampung Pisang Pisang, Sabah, Malaysia.

FIGURES 7 – 10. Habitus of: 7) Uietelmis jablonskii sp. nov., holotype ♂, BL: 1.76 mm; 8) U. brevicornis, ♂, BL: 1.80 mm; 9) U. kovaci, ♂, BL: 1.74 mm; 10) U. dentipes, paratype ♂, BL: 1.64 mm.

FIGURES 11 – 14. Head and pronotum of: 11) Uietelmis jablonskii sp. nov., holotype ♂; 12) U. kovaci, ♂; 13) U. dentipes, paratype ♂; 14) Uietelmis lantiri, paratype ♂.

FIGURES 17 – 19. Uietelmis jablonskii sp. nov., holotype: 17) aedeagus, ventral view; 18) ♂ sternite VIII; 19) ♂ pregenital segments. Scale bars 0.1 mm.