Copelatus baranensis, Hájek & Shaverdo & Hendrich & Balke, 2021

Hajek, Jiri, Shaverdo, Helena, Hendrich, Lars & Balke, Michael, 2021, A review of Copelatus diving beetles from the Solomon Islands, reporting the discovery of six new species (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 1023, pp. 81-118 : 81

Copelatus baranensis sp. nov. Figures 1 , 15

Type locality.

Solomon Islands, Guadalcanal , Barana Village area , Mount Austine, 09°28.0'S, 159°58.4'E .

Type material.

Holotype: ♂, labelled: " Solomon Islands, Guadalcanal / Mt. Austine - Barana vill. env. / (secondary forest, gardens, stream) / 09°28.0'S, 159°58.4'E; 280 m / Jiří Hájek leg., 23.xi.-8.xii.2013 [p] // HOLOTYPE ♂ / COPELATUS / Copelatus baranensis sp. nov. / Hájek, Shaverdo, Hendrich & Balke det. 2020 [red label, p]" ( NMPC) .

Paratypes: 1 ♂, 3 ♀♀, same data as holotype ( NMPC) ; 14 ♂♂, 17 ♀♀, labelled: " Solomon Islands, Guadalcanal / ca. 3.5 km SE of Barana vill. / (drying up stream in shaded gorge) / 09°29.8'S, 159°59.5'E; 190 m / Jiří Hájek leg., 24.xi.-14.xii.2013 [p]" ( NHMUK, NHMW, NMPC, ZSMG) ; 6 ♂♂, 6 ♀♀, labelled: " Solomon Islands, Guadalcanal / ca 4.5 km S of Barana vill., forest / nr. " Japanese camp" & Moka river / 09°30.3'S, 159°58.9'E; 275 m / Jiří Hájek leg., 5.-6.xii.2013 [p]" ( NMPC) ; 1 ♀, labelled: " Solomon Islands, Guadalcanal I. / Honiara reg. Barana vill. Env. / 100-300 m XI-XII.2018 / St. Jakl leg." ( LHCM) . All paratypes with the respective printed red label .

Description of male holotype.

Habitus: Elongate, oblong-oval, almost parallel-sided, broadest in mid-length of elytra; body moderately convex in lateral view. Body outline continuous, with only indistinct discontinuity between pronotum and elytra. Dorsal surface shiny (Fig. 1 ).

Colouration: Body colour brown blackish; head, sides of pronotum and appendages paler, ferruginous; base of elytra with irregular transverse testaceous band reaching neither suture nor lateral margin of elytra, band comb-like shaped due to dark colouration of elytral striae; appendages testaceous; ventral part brown blackish.

Head: Moderately broad, ca. 0.64 × width of pronotum, trapezoidal. Anterior margin of clypeus indistinctly concave. Antenna with antennomeres long and slender. Reticulation consisting of moderately deeply impressed polygonal isodiametric meshes. Punctation double, consisting of coarse setigerous punctures, and very small punctures spread sparsely on surface; row of coarse punctures present around inner margin of eyes, several punctures present at frontal level of eyes, and anterolaterally to eyes in fronto-clypeal depressions.

Pronotum: Transverse (width/length ratio = 2.54), broadest between posterior angles, lateral margins moderately curved. Sides with lateral beading very thin and indistinct. Reticulation similar to that of head. Punctation similar to that of head; rows of coarse setigerous punctures present along anterior margin, laterally in longitudinal depression close to sides, several punctures present also in basolateral depressions along basal margin. Disc of pronotum laterally with long, irregularly distributed longitudinal strioles; several strioles present also in depressions close to posterior angles. Centre of disc with medial longitudinal smooth line.

Elytra: Base of elytra as broad as pronotal base; lateral margins of elytra subparallel in basal two thirds, curved in apical third. Eleven longitudinal discal striae present on each elytron: stria 1 short, beginning at a fourth of elytral length and ending approximately before apical fifth of elytral length; striae 2 and 3 absent at base; striae 4-6 beginning at base; stria 7 fragmented basally; stria 8 complete; stria 9 absent at base and ending at apical fifth of elytra; stria 10 fragmented into several small strioles, hardly perceptible; stria 11 fragmented apically; all odd striae generally shortened apically. Submarginal stria absent. Surface reticulation similar to that of head and pronotum, meshes slightly smaller and less impressed. Punctation double, consisting of row of coarse setigerous punctures along elytral striae 4, 6, 8 and along lateral margin of elytra, and very fine sparsely distributed punctures.

Legs: Protibia simple, slightly broadened anteriorly, club shaped. Pro- and mesotarsomeres 1-3 distinctly broadened, with adhesive setae on their ventral side.

Ventral side: Prosternum sinuate anteriorly, obtusely keeled medially. Prosternal process shortly lanceolate, in cross-section convex, apex obtuse; process distinctly bordered laterally; reticulation consisting of shallow, hardly perceptible polygonal meshes. Metaventrite with microsculpture consisting of polygonal meshes; lateral parts of metaventrite ("metasternal wings") tongue-shaped, slender. Metacoxal lines well impressed, nearly complete, absent only close to metaventrite. Metacoxal plates covered with long, deep longitudinal strioles; reticulation consisting of elongated, longitudinal polygonal meshes. Metacoxal processes rounded and indistinctly incised at posterior margin. Abdominal ventrites I and II with longitudinal strioles; ventrites III and IV with oblique strioles laterally. Tuft of setae present antero-medially on ventrites III-V; ventrite VI with setigerous punctures laterally on either side. Abdominal reticulation consisting of elongate polygonal meshes, longitudinal on ventrites I and II, oblique on ventrite III and transverse on ventrites IV-VI. Punctation consisting of fine, sparsely distributed punctures; punctures coarser and denser laterally on apical ventrite.

Genitalia: Median lobe of aedeagus (Fig. 15 ) sickle-shaped, with obtuse apex and distinct rugose surface sculpture visible in lateral view (Fig. 15A, B ); consisting of dorsal and ventral sclerites; dorsal sclerite divided into two parts of different shape in apical half, left part slightly shorter than right one, with lateral margin distinctly curved and apex more or less rounded (Fig. 15C ); ventral sclerite with left part strongly sclerotised, its apex in shape of a small, weak hook visible in lateral left view (Fig. 15B ), right part membranous; apexes of dorsal and ventral sclerites more or less pressed together.

Lateral lobes (parameres) of narrow triangular form, with almost straight setigerous dorsal margin; setae numerous, dense, and strong distally, and distinctly less numerous, weaker, and sparser basally (Fig. 15D ).

Female. Identical to male in habitus. Pro- and mesotarsomeres not broadened, without adhesive setae.

Variability.

The specimens of the type series vary in extent of the basal testaceous band on elytra. There is also a variation in number and position of longitudinal strioles on pronotum. The highest variability is however, in elytral striation: from complete eleven striae to largely fragmented striae 1, 2, 4, 6, 7, 9, 10; in rare case, stria 1 completely absent; in several specimens, submarginal stria (or several short striae) present at the level of apical fifth of elytral length, sometimes only on one side.

Measurements.

TL: 5.4-6.2 mm (mean value: 5.7 ± 0.2 mm); holotype: 5.9 mm. TL-h: 4.9-5.7 mm (mean value: 5.2 ± 0.2 mm); holotype: 5.4 mm. MW: 2.4-2.9 mm (mean value: 2.6 ± 0.1 mm); holotype: 2.6 mm.

Differential diagnosis.

Based on the presence of 11 dorsal elytral striae and absence of submarginal stria, the new species can be classified within C. nigrolineatus species group. This group contain worldwide only five species: two in Neotropics, one in southern China, one in India, and one species in Australia ( Nilsson and Hájek 2020). On the other hand, presence of a submarginal stria in some specimens indicates affiliation of the new species to the C. trilobatus species group. The C. trilobatus species group includes up to now 24 species occurring in tropics of all continents; two species of the group are occurring in the Papua New Guinea, one species in Fiji, and three species are known from Australia ( Nilsson and Hájek 2020).

Based on shape of the male genitalia, C. baranensis sp. nov. is not similar to any of the species currently included in the C. nigrolineatus group. On the other hand, it is most likely very close to C. bougainvillensis sp. nov., C. kietensis sp. nov., and to the numerous undescribed species of the C. trilobatus species group from New Guinea (H. Shaverdo et al., in preparation). For separation of C. baranensis sp. nov., C. bougainvillensis sp. nov. and C. kietensis sp. nov., see under the two latter species.

Etymology.

The new species is named after Barana Village, in the vicinity of which the new species was collected. In this way, the first author would like to thank the people of Barana for their company and help with collecting during the 2013 trip. The specific epithet is an adjective in the nominative singular.

Distribution.

The species is known so far only from the small area around Barana Village, south from Honiara City, northern Guadalcanal .

Habitat.

At the type locality, the species was collected in small shaded pools of a forest stream (Figs 26 , 27 ). At the other places, the specimens were collected in puddles/pools with muddy bottom made by a temporary forest stream (Fig. 28 ).

Figures

Figure 15. Male genitalia of Copelatus baranensis sp. nov. (holotype) A median lobe in lateral view, right side B median lobe in lateral view, left side C median lobe in ventral view D left paramere in external view. Scale bar: 0.5 mm.

Figures 1, 2. Habitus of Copelatus 1 C. baranensis sp. nov. (holotype; TL: 5.9 mm) 2 C. bougainvillensis sp. nov. (holotype; TL: 5.2 mm).

Figures 26 - 28. Habitats of Copelatus in Guadalcanal 26 temporary forest stream near Barana village 27 shaded pool on the same stream 28 small temporary puddles in a gorge along the road from Barana to Lungga river.