Copelatus lanxangensis, Hájek & Sheth, 2024

Hájek, Jiří & Sheth, Sayali D., 2024, A review of the Oriental Copelatus latipes complex, with the description of two new species (Coleoptera: Dytiscidae: Copelatinae), Zootaxa 5481 (1), pp. 119-130 : 126-128

Copelatus lanxangensis sp. nov.

( Figs 5 , 15–16 )

Type locality. Laos, Khammouane Province, Nakai env., 17°43’N 105°09’E .

Type material. Holotype ♂ ( NMPC), labelled: “ LAOS centr.22.5- 8.6.2001 / Khammouan prov. 500–600 m, / NAKAI env., / N 17°43’, E 105°09’, / Jendek E. & Šauša O. leg. [p] // HOLOTYPUS ♂ / COPELATUS / lanxangensis sp. nov. / Hájek & Sheth det. 2024 [red label, p]” . Paratypes: 13 ♂, 17 ♀, same label data as holotype ( ASCG, BMNH, NMPC) ; 1 ♂, “ LAOS, Vientiane prov. / LAO PAKO env., 200 m / 55 km NE Vientiane [18°9’31’’N 102°51’28’’E] / 19.–22.V. 2004, J. Bezděk leg. ( NMPC). All paratypes with the appropriate printed red label.

Description of holotype. Habitus oblong-oval, with continuous outline, broadest at mid-length of elytra, slightly convex. Dorsal surface submatt.

Colouration. Head reddish brown, blackish around eyes and medially between eyes, lighter on clypeus, labrum and medially on vertex. Pronotum brown blackish, laterally reddish, pale colouration extending anteriorly; basal and anterior margin somewhat reddish translucent. Elytra brown blackish, with orange apex and sides laterally from elytral stria 6, and orangish pattern consisting of: two basal spots between striae 2–3 and 4–6; and longitudinal orange stripes beginning in second fourth between striae 3–5, and beginning subbasally between striae 5–6. Ventral surface reddish brown. Appendages orange to red ( Fig. 5 ).

Head. Moderately broad, ca. 0.62× width of pronotum, transversely elliptical. Anterior margin of clypeus indistinctly concave. Antenna with antennomeres long and slender. Reticulation consisting of fine, well impressed isodiametric polygonal meshes. Punctation double; several large setigerous punctures present in fronto-clypeal depressions, frontal depressions at level of anterior margin of eyes, and in depressions along inner margin of eyes; fine punctures smaller and sparser on clypeus, becoming larger and denser posteriorly.

Pronotum. Transverse (width/length ratio = 2.8), broadest between posterior angles, lateral margins moderately curved. Lateral sides with beading thin but distinct, except at anterior angles. Reticulation and punctation similar to that of head; rows of coarse setigerous punctures present along anterior margin and laterally close to sides; several punctures present also in shallow basolateral depressions along basal margin. Centre of disc with shallowly impressed medial longitudinal smooth line.

Elytra. Elytral striation consisting of six well impressed discal striae and one submarginal stria on each elytron: stria 1 beginning subbasally, striae 2–6 beginning at base of elytra; striae 1 and 4 ending close to apex, striae 2, 3 and 5 shorter than striae 1 and 4—not reaching apex of elytra; stria 6 shortest, ending approximately in apical fourth of elytral length; submarginal stria long, starting before elytral mid-length and terminating shortly before apex, at same level as dorsal striae 2, 3 and 5. Reticulation similar to that of head and pronotum, but less impressed. Punctation consisting of scattered very fine sparse punctures and coarse setigerous punctures present along elytral striae and lateral margins of elytra.

Legs. Protibia modified, angled near base, distinctly broadened anteriorly, club shaped. Pro- and mesotarsomeres 1–3 distinctly broadened, with four rows of adhesive setae on their ventral side; claws simple. Longer spur on metatibia sinuate in apical third.

Ventral side. Prosternum sinuate anteriorly, obtusely keeled medially. Prosternal process shortly lanceolate, in cross-section convex, apex obtuse; process distinctly bordered laterally; reticulation not perceptible. Metaventrite with microsculpture consisting of polygonal meshes; lateral parts of metaventrite (‘metasternal wings’) tongueshaped, slender. Metacoxal lines incomplete, absent in ca. anterior fifth of metacoxal length. Metacoxal plates covered with long oblique strioles; reticulation consisting of oblique elongate polygonal meshes. Metacoxal processes rounded at posterior margin. Abdominal ventrites I–II with longitudinal strioles; ventrites III–IV with oblique strioles laterally. Tuft of setae present medially on ventrites III–V; ventrite VI with setigerous punctures laterally. Abdominal reticulation consisting of elongate polygonal meshes, longitudinal on ventrites I–II, oblique on ventrite III and transverse on ventrites IV–VI. Punctation consisting of fine, sparsely distributed punctures.

Male genitalia. Median lobe of aedeagus in lateral view ( Fig. 15a ) broad in basal 2/3; apical third sickle-shaped, regularly curved and tapering distally, apex obtusely truncate; at 2/3 of its length with two distinct ‚teeth‘ on ventral side—broad rectangular proximal one, and medially incised and apically blunt distal one; third, small pointed tooth visible in ventro-lateral view ( Fig. 15b ). Parameres moderately broad, ‚D‘ shaped, with distinct lobe on inner margin, apex short and broad; apical lobe long, club-shaped ( Fig. 16 ).

Female. Female identical to male in habitus. Protibia simple, not angled basally and only slightly broadened distally; pro- and mesotarsomeres not broadened, without adhesive setae; longer metatibial spur straight. Dorsal surface with reticulation slightly more impressed and thus appearing matt. Pronotum baso-laterally with several irregular striolae. Few weakly impressed short striolae present in middle part of elytra between elytral striae 5 and 6.

Variability. Specimens of the type series vary slightly in colouration, especially in infuscation of head and pronotum (from brown to nearly black) and elytra (from reddish brown to brown); some variation can be seen also in the extent of the orange colouration laterally on pronotum and elytra. In some specimens, elytral stria 1 is fragmented or absent in basal fourth of elytral length. The extent of the striolate elytral surface varies in females—in some specimens striolae are present in the middle part part of the elytra lateral to stria 2.

Measurements. TL: 5.2–6.2 mm (mean value: 5.7 ± 0.2 mm); holotype: 5.9 mm. TL-h: 4.7–5.6 mm (mean value: 5.1 ± 0.2 mm); holotype: 5.3 mm. MW: 2.7–3.1 mm (mean value: 2.9 ± 0.1 mm); holotype: 3.0 mm.

Differential diagnosis. Based on the presence of six dorsal striae and a submarginal elytral stria, Copelatus lanxangensis sp. nov. can be classified within the Copelatus irinus group sensu Guignot (1961). The characteristic shape of the median lobe with two ‘teeth’ on the ventral side ( Fig. 15 ) places the new species to the newly proposed C. latipes complex. The new species is most similar to the partly sympatric C. latipes . Both species can be easily distinguished by the elytral striation: while stria 1 begins subbasally or at most in basal fourth of elytral length in C. lanxangensis sp. nov., it is largely absent and beginning in apical fifth in C. latipes (see Figs 5 and 6 ). In addition, C. lanxangensis sp. nov. can be distinguished from all other Copelatus species by the shape of the male genitalia, especially by the regularly curved apical third of the median lobe, the broad rectangular proximal median ‘tooth’ and the medially incised and apically blunt distal tooth ( Fig. 15 ).

Etymology. The species is named after Lan Xang or Lancang, a Lao kingdom that held the area of present-day Laos from 1353 to 1707. The specific name is an adjective.

Distribution. The species is so far only known from two localities in central Laos ( Fig. 19 ).

Figures

FIGURE 19. Map of distribution of Copelatus latipes species complex.

FIGURES 3–6. Habitus of Copelatus latipes species complex. 3. C. brivioi (♂; West Bengal, India); 4. C. kopetzi sp. nov. (holotype ♂; Nepal); 5. C. lanxangensis sp. nov. (holotype ♂; Laos); 6. C. latipes (♂; Pahang, Malaysia). Scale bar 2 mm.

FIGURES 7–18. Male genitalia of Copelatus latipes species complex. 7, 9, 11, 13, 15, 17. median lobe in lateral (a) and ventro-lateral (b) view; 8, 10, 12, 14, 16, 18. paramere. 7–8. C. bezdeki (holotype; Maharashtra, India); 9–10. C. schereri (Sri Lanka); 11–12. C. brivioi (paratype; Bangladesh); 13–14. C. kopetzi sp. nov. (holotype; Nepal); 15–16. C. lanxangensis sp. nov. (holotype; Laos); 17–18. C. latipes (Pahang, Malaysia). Scale bar 0.5 mm.