Byrrhinus negrosensis, Delocado & Freitag, 2021

Delocado, Emmanuel D. & Freitag, Hendrik, 2021, Two new species of Byrrhinus Motschulsky, 1858 (Coleoptera, Limnichidae, Limnichinae) from Negros, Philippines, ZooKeys 1070, pp. 51-72 : 51

Byrrhinus negrosensis sp. nov.

Figures 2 , 4 , 5

Type locality.

Philippines • Negros Island, Negros Oriental, Valencia, Casaroro River, in secondary vegetation; ca. 09°18'N, 123°14'E; ca.150 m a.s.l.

Type material.

Holotype: Philippines • ♂ (PNM: EDD122), "PHIL: Negros Or., Valencia, \ Casaroro River, downstr., sec.veg.; \ ca. 09°18'N; 123°14'E; ca.150 m a.s.l.; \ 01 Sep. 2019, leg. Garces & Pelingen (655)L"; GenBank: OK316808; BOLD: COLPH054-21; EDD122, habitus and terminal parts of abdomen including genitalia glued separately on to entomological card. Paratypes: Philippines • 3♂♂ (ADMU: EDD123, EDD127): same data as holotype; GenBank: OK316803, OK316809; BOLD: COLPH055-21, COLPH056-21 • 3♂♂, 3♀♀: (ADMU: EDD116, EDD119, EDD270; PNM; ZMB) "PHIL: Negros Occ., Murcia, \ Pandanon River, sec.veg.; \ ca. 10°34'54"N; 123°10'30"E; ca. 440 m a.s.l.; \ 01 May 2019, leg. Freitag et al. (650)L"; GenBank: OK316807, OK316811, OK316812; BOLD: COLPH052-21, COLPH053-21, COLPH057-21.

Description.

Body: (Fig. 2 ) elongate-oval, TL = 3.2 mm (2.9-4.1 mm), EW = 2.1 mm (1.8-2.3 mm), widest behind mid-leg; dorsal surface brown to dark brown; body appendages slightly paler than body, moderately densely and evenly covered with yellow-brown to brown, fine, quite long, mostly erect pubescence; antennae yellow-brown to brown; femora and tibiae brown; tarsi brown.

Head: obscurely rugulose; broadly laminate over eyes; margins of frons grooved over eyes; sides of frons with deep and well-marked pit-like depressions. Punctation minute, sparse, slightly coarser near epistomal suture. Pubescence dense and erect in anterior regions, sparse and recumbent posteriad. Eyes slightly convex, visible from above; upper margin of eyes strongly bordered, margin anteriorly almost reaching insertion of antennae, extending posterior of eyes although weaker. Surface of head posterior to eyes flat, without depressions or fossae; surface with fine and sparse punctation, denser and coarser on clypeus; surface between punctures smooth and shiny. Antennae moniliform, strongly pubescent; pedicel oblong, brown, slightly darker than adjacent antennomeres; antennomeres longer than wide, brown, darker distally, terminal antennomeres asymmetrical and darker than pedicel; pubescence brown, of two series: first series composed of one to two pairs of long and erect pubescence per antennomere, about as long as antennomere and second series composed of denser, shorter, paler, recumbent pubescence.

Pronotum: transverse, slightly paler on sides than on disc, distinctly wider at base; anterior margin of pronotum slightly concave, but almost straight between eyes, without crenulations, bordered; lateral margins only slightly arched, posterolateral angle 75-80°, with prominent borders; posterior margin with a distinct double sinuation; PL/PW = 0.42 (0.40-0.43); PW/PL = 2.40 (2.30-2.51). Punctation dense, minute and shallowly impressed; punctures larger than that of the head, denser at median line and posterior margins, sparse near suture and anteriad; surface between punctures rugose. Pubescence similar to the erect series of the head, denser on the anterior one-third of the lateral margin, evenly spaced on the rest of the margin, very sparse to almost obsolete and slightly decumbent proximally. Hypomeron flat, without depressions or fossae.

Elytra: EL/EW = 1.36 (1.30-1.43); EL/PL = 3.63 (3.63-3.85); EW/PW = 1.23 (1.16-1.27); TL/EW = 1.78 (1.66-1.78), slightly less than 4.0 times longer than the pronotum, widest at anterior 0.25; anterior margin of elytra bordered, bi-sinuately articulated with pronotum; lateral margins slightly explanate in anterior half; apices jointly rounded; humeral callus weak. Elytra with two series of punctation; first series with nine or more perceptible and irregular rows of large, deeply impressed punctures; punctures of medial five rows denser and more strongly impressed in anterior half; increasingly scattered, finer and more shallowly impressed laterally and posteriorly; intervals and interstices distinctly broader than punctures; second series of punctures much smaller, densely and evenly distributed over entire elytra. Pubescence long, yellowish-brown to brown, of two distinct types (erect and recumbent): erect series on sides, slightly recumbent series on disc; erect series longer and denser; recumbent series shorter, very sparse. Scutellum subtriangular, with irregular and densely punctured surface; with two series of punctation, few large and deeply impressed punctures, numerous finer and shallowly impressed ones; pubescence erect, sparse. Metathoracic wings well developed. Epipleura almost flat.

Ventral surface: punctation dense and almost uniform; pubescence brown, minute, long, finer than on dorsal side, recumbent, dense and evenly distributed. Prosternum slightly impressed at the process; process narrow, punctation more distinct at tip. Mesosternal ridge along posterior margins of mesosternum distinct. Metasternum perforate at sides, with raised triangular, rugulose area behind mesocoxal cavities; raised area comprising nearly half of surface; metasternal ridge along posterior margin of metasternum faint laterally, well-developed medially. Abdominal punctation finer at mid-line than at sides; surface between punctation with polygonal network, with median pore. Intermetacoxal plate on ventrite I triangular, strongly acuminate. Abdominal ventrite I with depressions for reception of metafemora and metatibiae; ventrites I-III connate, fused; ventrites IV-V without polygonal network; ventrite V distinctly emarginate.

Legs: less than half of body length. Tibia brown, lateral margins darker, distal margin with comb of long spines; protibia very short, a little longer than half of either mesotibia and metatibia, lateral margin slightly concave, setae denser than on mesotibia and metatibia; mesotibia with lateral margin curved more prominently in interior margins, setae evenly distributed; metatibia almost twice as long as protibia, slightly longer than mesotibia, lateral margins almost parallel, setae sparse and almost recumbent; apex of mesotibia and metatibia smoothly and broadly curved. Tarsi 5-5-5, brown, paler towards the apex, almost half as long as mesotibia; tarsomere length ratio ca. 1.0:1.0:1.0:1.0:4.0 (0.9-1.1: 0.9-1.1: 0.9-1.1: 0.9-1.1: 3.5-4.7); tarsomere 1 widest towards the apex, distal margin almost double the width of proximal margin, with dense comb of setae; tarsomeres 2-4 similar to tarsomere 1, but outer edge with long yellow spiny setae on both sides, remaining portions with sparse minute setae; tarsomere 5 widest towards the apex, almost triangular, with long robust spiny setae. Tarsal claws long, narrow, symmetrical.

Male genitalia: (Figs 4 , 5 ) length 0.67 mm (0.65-0.71 mm), width 0.11 mm (0.10-0.14 mm), very slender, strongly sclerotised; median lobe more exposed in ventral view than dorsal view. Median lobe of aedeagus almost as long as parameres, symmetrical; apex flat, broad, most slender subapically, with pair of rows of short denticles subapically (ventral view), convexly widened basally; basal portion wider than apical portion. Parameres symmetrical; apices slender and moderately separated dorsally, broader and converged ventrally, inner margin of parameres subparallel near tips, distinctly concave in the middle converging basally in V-shape; with tubular lobes protruding medio-apically in apical third below the denticles of the median lobe, median gap wider dorsally and exposing the full width of median lobe. Basal lobe asymmetrical, with strongly sclerotised basal margins. Ventrite VIII U-shaped, with narrow apical membranous lamina. Spiculum prominent.

Female genitalia: ovipositor relatively short (0.58-0.62 mm long), straight.

Differential diagnosis.

In the elongate oval shape, the new species resembles several species, including B. ferax and B. tarawakanus . Amongst the Philippine species, the range of size overlaps with B. subtestaceus and B. ferax . The protibia of B. negrosensis sp. nov. is notably smaller than the mesotibia and metatibia. The male genitalia of B. negrosensis sp. nov. resembles that of B. ferax due to the medially parallel paramere apices, which is quite uncommon in the Oriental members of the genus. Despite numerous similarities, B. negrosensis sp. nov. differs from B. ferax in the dorsally V-shaped basal fusion point of the parameres (Fig. 4 ), while the latter possesses a U-shape parameral fusion. B. negrosensis sp. nov. varies by 13.2% mean genetic distance (723 bp COI-3 ' mtDNA barcode) from the most similar B. ferax and by at least 16.1% from any other Philippine congener with available barcode (Suppl. material 1: Table S1).

Distribution.

This species is only recorded from the Island of Negros in the Philippines.

Remarks.

No external sexual dimorphism is observed. Teneral specimens are significantly paler brown.

Etymology.

The species is named after the Island of Negros from where the specimens were collected.

Figures

Figures 2, 3. Habitus of new Byrrhinus species 2 Byrrhinus negrosensis sp. nov. 3 Byrrhinus villarini sp. nov. Scale bar: 1 mm.

Figures 4 - 7. Male aedeagi of 4, 5 Byrrhinus negrosensis sp. nov. (EDD 122) and 6, 7 Byrrhinus villarini sp. nov. (EDD 121) in (4, 6) dorsal and (5, 7) ventral views. Scale bar: 0.25 mm.