Parahelichus pseudogranulosus, Lojková, Soňa, Degma, Peter & Kodada, Ján, 2014

Lojková, Soňa, Degma, Peter & Kodada, Ján, 2014, Morphometry and redescription of Parahelichus granulosus (Delève, 1974) with description of P. pseudogranulosus, a new cryptic species of Long-toed Water Beetles (Coleoptera: Dryopidae) from Indochinese peninsula, and proposal of a new synonym for Praehelichus sericatus (Waterhouse, 1881) from China, Zootaxa 3852 (4), pp. 475-488 : 480-487

Parahelichus pseudogranulosus sp. nov.

Type locality. Pakka Ding, Bolikhamxai province, Central Laos.

Etymology. The name is a combination of the prefix pseudo (apparently similar) and granulosus in reference to the very similar appearance as P. granulosus .

Material examined. Holotype ♂ ( NMW): “LAOS-C, 26.-27.V.2003, Bolikhamxai prov., PAKKA DING, ~ 300 m, 18°20´N 104°00´E, Vít Kubáň leg.“ Paratypes. 1♂ ( CKB): “NW THAI 23.-31.V. MAE HONG SON 1200 m, Ban Si Lang 1991, J. Horák leg.“; 1 ♂ ( NMW): “ LAOS centr., Khammouan prov., 10.-13.VI.2001, Ban Khoun Ngeun env. 18°07´N 104°29´E, alt. 250 m, E. Jendek & O.Šauša leg.“. Non type material of presumed conspecific females. 2 ♀♀ ( CKB): “LAOS-C, 26.-27.V.2003, Bolikhamxai prov., PAKKA DING, ~ 300 m, 18°20´N 104°00´E, Vít Kubáň leg.“; 2 ♀♀ ( CKB): “ LAOS centr., Khammouan prov., 10.-13.VI.2001, Ban Khoun Ngeun env. 18°07´N 104°29´E, alt. 250 m, E. Jendek & O.Šauša leg.“.

Differential diagnosis. P. pseudogranulosus is externally very similar to P. granulosus . Males and females of both species cannot be recognized from each other according to metric characters as their ranges overlap. The only exceptions are values of aedeagus proportions: phallobase in P. pseudogranulosus is 2.00–2.22 times as long as parameres, while the ratio is 1.14–1.77 in P. granulosus . These higher values for this character were shown to clearly separate males of P. pseudogranulosus from those of P. granulosus in the PCA (Fig. 33). Except for this difference, the flat larger granules on pronotum and elytra of P. pseudogranulosus look a little bit smaller than in P. granulosus .

Since it is not possible to unambiguously assign females to P. granulosus or P. pseudogranulosus , we arbitrarily ascribed four females to P. pseudogranulosus of the basis of co-occurence with males of P. pseudogranulosus . Therefore, they presumed females were not included into types.

Description. Habitus of male as shown in Fig. 2. Body elongated, moderately convex dorsally. Length (BL) in ♂♂: 5.21–6.63 mm (5.71 ± 0.80), in ♀♀: 5.32–6.71 mm (5.89 ± 0.65); maximum width (EW) in ♂♂: 2.24–2.66 mm (2.39 ± 0.24), in ♀♀: 2.24–2.89 mm (2.53 ± 0.35). Colour nearly black, antennal clubs, mouthparts and tarsi reddish-brown.

Surface opaque; densely covered with small rounded granules and larger shiny flat ones. Small granules about one third of a diameter of a facet. Larger granules moderately smaller than facet, nearly rounded and more or less regularly arranged, associated with yellowish setae. Elytra lacking distinct striae and intervals.

methods.

Head wider than long; surface shiny with sparse granules and fine punctures; granules distinctly smaller than a facet diameter, associated with yellowish recumbent setae; granules and punctures irregularly spaced, more densely arranged on lateral portion of clypeus. Frontal region with a small shiny longitudinal area. Eyes large, protuberant, strongly facetted; interfacetal setae fine, scattered, confined to central portion. ID in ♂♂: 0.55–0.76 mm (0.62 ± 0.12), in ♀♀: 0.58–0.79 mm (0.66 ± 0.10); HW in ♂♂: 1.05–1.32 mm (1.14 ± 0.15), in ♀♀: 1.11–1.37 mm (1.23 ± 0.12).

Thorax. Pronotum wider than long; disc convex dorsally; larger granules more distinct than those on head, separated usually by distance of more or less one granule diameter. Lateral pronotal carina distinct; sides moderately arcuate to sinuate; posterior angles nearly rectangular, moderately acute; anterior angles acute, deflected and strongly protruding; posterior margin trisinuate, smooth; prescutellar foveae absent. MPL in ♂♂: 1.13–1.47 mm (1.25 ± 0.19), in ♀♀: 1.21–1.45 mm (1.32 ± 0.10); APW in ♂♂: 1.18–1.45 mm (1.28 ± 0.14), in ♀♀: 1.21–1.53 mm (1.37 ± 0.14); PPW in ♂♂: 1.58–2.11 mm (1.82 ± 0.27), in ♀♀: 1.58–2.11 mm (1.86 ± 0.28). Hypomeron widest near middle, distinctly narrowed anteriorly and slightly posteriorly; separated from prosternum by a gap along anterior third. Prosternum in front of coxae approximately as long as prosternal process, anterolateral portion rounded. Setae in middle of prosternum and on prosternal process longer than those on dorsal surface, longest setae in middle of metaventrite. Prosternal process wide, strongly overlapping mesoventrite, apex subacute; sides raised. Scutellum (scutellar shield) large, broadly rounded, in same level with elytra, surface granulated. Metaventrite distinctly longer than prosternum in front of coxae; discrimen distinct along entire length, in depression; transverse suture fine. Elytra convex dorsally; lateral margin not explanate; gradually extended posteriad from shoulders up to 0.75 of their length; shoulders rounded, prominent; elytral apices nearly acute; granulation on elytra similar to that on pronotum but less dense, granules more or less regularly spaced; epipleura widest basally, inflected at level of metacoxa and near apex, partly concealed by lateral margin of ventrites. EW in ♂♂: 2.24–2.66 mm (2.39 ± 0.24), in ♀♀: 2.24–2.89 mm (2.53 ± 0.35); EL in ♂♂: 4.05–5.16 mm (4.46 ± 0.61), in ♀♀: 4.11–5.26 mm (4.57 ± 0.57). Legs slightly longer than elytra; femora strongly widened, widest near middle, with scattered fine punctures. Tibiae slightly longer than femora, apically widened: especially apex of pro- and metatibia; each tibia weakly curved, narrow. Tarsi approximately as long as protibia and mesotibia, respectively; slightly shorter than metatibia, with few short strong setae ventrally and longer setae mainly dorsally and laterally; terminal tarsomere of metatibia slightly shorter than combined lengths of tarsomeres 1–4, those on pro- and mesotibia approximately as long as combined lengths of tarsomeres 1–4.

Abdomen with ventrite 1 longest, ventrite 5 posteriorly slightly excised in males and rounded in females. Segments VIII and IX sexually dimorphic. Male segment VIII: sternite gently rounded posteriorly, not emarginated, distinctly shorter than ventrite 5, with short median symmetrical process anteriorly; tergite more strongly sclerotized laterally than mesally, rounded posteriorly. Female segment VIII: sternite posteriorly subtriangular, sclerotized laterally, with anterior median process approximately half as long as abdomen; tergite similar to that of male. Male sternite IX with anterior median process nearly as long as ventrites 4–5 combined, process narrow and long; female sternite IX forming a part of ovipositor.

Aedeagus ( Figs 21–23, 26–31 ), with phallobase narrow, very long, subcylindrical, moderately curved, 2.00–2.22 (2.15 ± 0.13) times as long as parameres, almost as wide basally as apically (lateral view), with basal orifice asymmetrical, large; parameres individually articulated with phallobase, widest basally, short, slightly curved ventrad and gradually narrowed toward apices; apices rounded in lateral and ventral view. Penis narrow, symmetrical, moderately shorter than parameres, widest basally, gradually narrowed apically; apex subacute (ventral view); membranous ventral sac with fine longitudinal furrows; fibula narrow, reaching middle of penis (ventral view).

Ovipositor about as long as ventrites 3–5 combined, strongly sclerotized. Bursa copulatrix tubular, without sclerotized spinules.

Sexual dimorphism. Intersexual differences in metric characters were not found, as their values overlap between males and females. Females are recognized only on the basis of the shape of the apex of the fifth ventrite.

Variability. Specimens vary in size and arrangement of larger flat granules on surface. In the holotype, the granules on pronotum and elytra are distinctly smaller than facet and are separated by a distance larger than one facet diameter. On the other hand, the granules of paratypes are subequal to the diameter of a facet and are more densely arranged. The pronotal form varies moderately in curvature of sides from evenly arcuate to slightly sinuate.

Distribution. As yet known from Laos and Thailand ( Fig. 32 ). However, the distribution pattern is probably different from that of P. granulosus .

Note. Except for two species treated above, we have examined two other similar taxa from this small species complex. They came from India and differ from P. granulosus and P. pseudogranulosus in the form of elytra and pronotum. However, all Indian specimens investigated are females and, therefore, we keep from describing new species for them.

FIGURE 33. Morphometric analyses of males of Parahelichus granulosus (n = 202) and P. pseudogranulosus sp. nov. (n = 3), documenting that both taxa represent distinct species. (A) Box-plot graph to show the variation of aedeagus proportions (ratio of length of parameres to length of phallobase) of P. granulosus and P. pseudogranulosus sp. nov. Rectangles represent the 25th and 75th percentiles, horizontal lines show the median, whiskers are from the 10th to the 90th percentiles, and asterisks denote the extreme values. (B) PCA of males of P. granulosus and P. pseudogranulosus sp. nov. based on 12 metric characters. Eigenvalues of two first axes are λ1 = 0.9985 and λ2 = 0.0010, explaining 99.95% of the total variation.

Explanations and colour code of P. granulosus populations: YB (blue)—specimens from Yen Bai [ Vietnam], SP (orange)—specimens from Sa Pa [ Vietnam], LN (red)—Louang Namtha [ Laos], KR (green)—Khan river [ Laos], BK (yellow)—Ban Khoun Ngeun env. [ Laos]. Specimens of P. pseudogranulosus sp. nov. are shown as black circles in the PCA diagram.

Figures

FIGURE 32. Geographical distribution of Parahelichus granulosu s (black squares) and P. pseudogranulosus sp. nov. (black circles).

FIGURES 21 – 31. Parahelichus pseudogranulosus sp. nov., male; (21 ‒ 23, 26 – 31) aedeagus, penis and parameres in lateral, ventral and dorsal view; (21, 26, 27) a male from the locality Mae Hong Son, Ban Si Lang, Thailand; (22, 28, 29) a male from the Bolikhamxai province, Laos; (23, 30, 31) a male from the Khammouan province, Ban Khoun Ngeun env., Laos; (24) male sternite VIII, ventral view; (25) male sternite IX, ventral view. Scale 0.1 mm.