Platambus binliui, Hájek & Zhang, 2019

Hájek, Jiří & Zhang, Tao, 2019, A new Platambus from Sichuan, with new records of species of the P. sawadai group from China (Coleoptera: Dytiscidae: Agabinae), Zootaxa 4612 (4), pp. 533-543 : 534-536

Platambus binliui sp. nov.

( Figs 1–5 )

Type locality. China, Sichuan Province, Xiao-Zhaizi National Nature Reserve, 7 km W of Qingpianxiang, Xiaozhaizi , 32°01'25"N, 103°56'21"E, 1560–1700 m a.s.l.

Type material. Holotype: ♂, “ China, N Sichuan, Xiao-Zhaizi Nat. / Nature Reserve, 7 km W of / Qingpianx- iang, ṬṘŦ Xiaozhaizi / 32° 1'25"N 103°56'21"E / 27.6.– 1.7.2017, 1560–1700m / lgt. Ondřej Konvička, at light [printed] // HOLOTYPE ♂ / PLATAMBUS / binliui sp. nov. / J. Hájek & T. Zhang det. 2019 [red label, printed]” ( IZCAS) . Paratypes: 2 ♂, 3 ♀, same label data as holotype ( NMPC, OKCZ) ; 4 ♂, 5 ♀, “ China, N Sichuan /Xiao- Zhaizi National Nature Reserve / 7 km W of Qingpianxiang / ṬṘŦ Xiaozhaizi / 32° 1'25"N 103°56'21"E / 27.6.– 1.7.2017, 1560– 1700m / P. Viktora lgt. [printed]" ( BMNH, NHMB, NHMW, NMPC, SUCC) ; 1 ♂, 4 ♀, " China, N Sichuan, Xiao-Zhaizi / National Nature Reserve, 4 km / NNE of Qingpianxiang, AEOi" / Zhenghecun , 32° 3’27”N 103°59’37”E / 23.– 26.6.2017, 1350–1850m / lgt. Petr Kabátek [printed]” ( NMPC, ZSMG) . Each paratype is pro- vided with the respective red printed label.

Description of male holotype. Habitus ( Fig. 1 ) elongate oblong oval, distinctly convex with continuous outline in dorsal view, broadest before half of elytral length, dorsally convex. Dorsal surface submatt due to coarse punctation.

Coloration. Dorsal surface almost uniformly black; head somewhat paler, indistinctly rufous on vertex, along eyes and on clypeus; pronotum indistinctly rufous along anterior and lateral margins, and medially on disc; elytra laterally posterior to mid-length with indistinct, longitudinal reddish spot. Ventral surface rufous; prosternal process, metacoxal processes and basal part of apical abdominal ventrites darker ( Fig. 2 ). Appendages rufous, metatibia and basal metatarsomeres somewhat darker.

Head. Moderately broad, ca. 0.65× width of pronotum, transversely elliptical. Anterior margin of clypeus truncate. Antennae with antennomeres slender, club-shaped, antennomere I longest. Eyes emarginate anterolaterally. Punctation double; several large setigerous punctures present on frons and in depressions along inner margin of eyes; fine punctures distributed sparsely and irregularly on head surface. Reticulation consisting of heterogeneous polygonal meshes; meshes usually with several micropunctures inside.

Pronotum. Transverse, broadest at posterior angles. Anterior angles acute with a tuft of thick setae, posterior angles rectangular. Sides slightly and evenly curved, with distinct lateral beading. Anterior margin straight (dorsofrontal view), posterior margin slightly sinuate. Punctation double; row of coarse setigerous punctures present along anterior and posterior margins; fine punctures distributed irregularly on pronotal surface, sparsely on disc and more densely laterally close to sides. Reticulation similar to that of head, consisting of heterogeneous polygonal meshes; meshes sometimes not closed, usually with several micropunctures inside. Reticulation rather weakly impressed on disc, becoming more impressed laterally and forming short wrinkles near sides. Centre of pronotal disc with distinct longitudinal furrow.

Scutellar shield broadly triangular.

Elytra. With distinct double punctation; coarse punctures arranged more or less serially, ca. 5× bigger than fine punctures spreading irregularly between them. Reticulation consisting of weakly impressed polygonal meshes; each mesh usually with several micropunctures.

Legs. Pro- and mesotibiae club shaped, on its ventral surface densely punctured with spinigerous punctures. Pro- and mesotarsomeres 1–3 slightly broadened, ventrally with adhesive setae. Metatarsomeres with well-developed natatorial setae on both sides. Surface of legs with distinct reticulation consisting of elongate oblique or transverse meshes.

Ventral surface ( Fig. 2 ). Genae with distinct oblique rectangular or polygonal meshes. Gula mostly smooth, with indistinct transverse reticulation and coarse punctation anteriorly, and with several fine punctures baso-laterally. Prosternum sinuate anteriorly, obtusely keeled medially. Prosternal column shiny, with sparse double punctation; slopes of prosternal column densely and coarsely punctate. Prosternal process shortly lanceolate, in cross-section flat, medially depressed; distinctly bordered in basal half, apex obtuse; surface with distinct double punctation ( Fig. 3 ). Metaventrite without microsculpture, shiny, with double punctation similar to that of prosternal process; lateral parts of metaventrite (‘metasternal wings’) tongue-shaped, slender. Metacoxal lines well impressed, complete, slightly divergent anteriad. Metacoxal plates coarsely and densely punctured with few fine punctures intermixed among coarse punctures; due to coarse punctation reticulation indistinct, well visible only along medial and posterior margin of plates. Numerous short elongate, possibly stridulatory striae present along posterior margin of metacoxal plates. Abdominal ventrites I–V with fine longitudinal (ventrite I), oblique (II–III) or transverse (IV–V) strioles; shiny, reticulation consisting of fine polygonal meshes present only at base of ventrites V and VI. Puncta- tion rather coarse on ventrite I, fine and sparse, distinctly double on ventrites II–V; several setigerous punctures presenting medially on ventrites III–V. Apical abdominal ventrite (VI) with numerous irregular wrinkles replacing reticulation on most of its surface, punctation double; ventrite with small depression before apex, apex shallowly emarginated.

Male genitalia. Median lobe in lateral aspect slender, gently and almost evenly curved throughout its length, apex shortly pointed ( Fig. 4a ). Median lobe in ventral view broad medially, narrowing slightly to rather blunt apex; indistinctly turned to right ( Fig. 4b ). Parameres ‘D’-shaped; apex very narrow and long, densely setose ( Fig. 5 ).

Female. Females do not differ in external morphology from males except for slender protibial, and pro- and mesotarsomeres I–III without adhesive setae; apical abdominal ventrite without preapical depression, apex nearly regularly rounded.

Variability. All specimens of the type series are very uniform, and vary slightly only in coloration: extension of lighter rufous colour on head and pronotum, and size and brightness of reddish spot on elytra (which is almost imperceptible in some specimens).

Measurements (N = 20). TL: 7.8–8.6 mm (mean value: 8.3 ± 0.2 mm); holotype: 8.4 mm. Tl-h: 7.1–7.8 mm (mean value: 7.4 ± 0.2 mm); holotype: 7.6 mm. MW: 4.4–4.9 mm (mean value: 4.7 ± 0.1 mm); holotype: 4.7 mm.

Differential diagnosis. The new species is notably larger than any other species of the group from China. It overlaps in body size with Platambus wangi Brancucci, 2006 from Hubei ( Fig. 9 ), but the average length of P. wangi is only 7.9 mm, while the average body length of the new species is 8.3 mm. In addition, P. binliui sp. nov. differs from that species in the less coarse punctation of elytra, weaker elytral reticulation, and primarily in the different shape of the median lobe of aedeagus which is broadened apically both in lateral and ventral view in P. wangi (cf. Brancucci 2006: Figs 2–3 ). The median lobe of the new species is rather similar to that of P. elongatus Bian & Ji, 2008 from Hainan and P. regulae Brancucci, 1991 from northern Laos and Vietnam; however, both these species are distinctly smaller, with different punctation of elytra, and the latter species is also more elongate (cf. Fig. 10 ).

Etymology. The new species is named in honour of Bin Liu (Beijing, China), an enthusiastic amateur entomologist and a specialist on Cerambycidae . The name is a noun in the genitive case.

Collecting circumstances. Few specimens were collected directly in the fast flowing mountain streams, ca. 5–7 m wide, with a gravelly bottom ( Figs 6–7 ); however, the majority of specimens were attracted to a light trap set near the stream. The new species was associated with Agabus brandti Harold, 1880 and Platambus angulicollis (Régimbart, 1899) (both Dytiscidae ).

Distribution. The species is known from two close localities (ca. 6 km apart) in northern Sichuan, China ( Fig. 20 ).

Figures

FIGURE 20. Map of distribution of Platambus sawadai group in China.

FIGURES 1–5. Platambus binliui sp. nov. 1. dorsal habitus of male holotype; 2. ventral habitus of male paratype; 3. prosternal process; 4. median lobe in (a) lateral and (b) ventral view; 5. paramere. Scale bar 1 mm (Figs. 3–5).

FIGURES 8–11. Habitus of Platambus sawadai group in China. 8. P. micropunctatus (Heishiding, Guangdong); 9. P. punctatipennis (Tianmu Shan, Zhejiang); 10. P. regulae (Jizu Shan, Yunnan); 11. P. wangi (Daba Shan, Hubei). Scale bar 2 mm.

FIGURES 6–7. Habitat of Platambus binliui sp. nov. 6. Mountain stream in Xiaozhaizi; 7. Zhengzehun (photos O. Konvička).