Byrrhinus villarini, 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 villarini sp. nov.

Figures 3 , 6 , 7

Type locality.

Philippines • Negros Island, Occidental Mindoro, Murcia, Pandanon River in secondary vegetation; ca. 10°34'54"N, 123°10'30"E; ca. 440 m a.s.l.

Type material.

Holotype: Philippines • ♂ (PNM: EDD121), "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: OK316813; BOLD: COLPH061-21; EDD121, habitus and terminal parts of abdomen including aedeagus glued separately on to entomological card. Paratypes: Philippines • 3♂♂, 4♀♀ (AdMU: EDD113, EDD114; PNM; ZMB: EDD115): same locality data as holotype; GenBank: OK316804, OK316815, OK316817; BOLD: COLPH058-21, COLPH059-21, COLPH060-21 • 3♂♂ (AdMU: EDD124, EDD126): "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: OK316805, OK316818; BOLD: COLPH062-21, COLPH063-21.

Description.

Body: (Fig. 3 ) ovoid, TL = 2.8 mm (2.2-2.9 mm), EW = 1.9 mm (1.4-1.9 mm), widest behind mid-leg; dorsal surface very dark-brown to black; body appendages slightly paler than body, moderately densely and evenly covered with brown, fine, quite long, mostly erect pubescence; antennae yellow-brown; femora and tibiae brown; tarsi dark yellowish, but darker on terminal ends of segments.

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, slightly coarser near epistomal suture. Pubescence brown, fine, quite long, erect, more numerous and denser on the anterior region. Eyes slightly convex, visible from above; upper margin of eyes bordered; anterior margin 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 globular, brown, darker than adjacent antennomeres; antennomeres longer than wide, yellow-brown; pubescence brown, uniform, erect, mostly as long as antennomere.

Pronotum: transverse, black, with dark brown colouration on the sides, distinctly narrower at base; anterior margin of pronotum straight, without crenulations, bordered; lateral margins strongly arched, posterolateral angle ca. 50°, with prominent borders; posterior margin with distinct double sinuation; PL/PW = 0.42 (0.40-0.44); PW/PL = 2.40 (2.28-2.50). Punctation strong and deeply impressed, but sparse; punctures stronger than that of the head, larger at posterior margins, sparse near suture and anteriad, surface very depressed at projections along posterior margin. Pubescence similar to that on the head, slightly decumbent near the median line, denser at sides. Hypomeron flat, without depressions or fossae.

Elytra: EL/EW = 1.41 (1.30-1.41); EL/PL = 4.14 (4.11-4.14); EW/PW = 1.20 (1.20-1.21); TL/EW = 1.75 (1.68-1.78); elytra slightly more than 4.0 times longer than the pronotum; widest at anterior 0.2; anterior margin of elytra bordered, strongly bi-sinuately articulated with the pronotum; lateral margins pronounced, finer towards apex; apices jointly rounded; humeral callus weak. Elytra punctation of two series; first series with nine or ten distinct and almost regular rows of large deeply impressed punctures; increasingly scattered, finer, not as strongly impressed as in rows laterally and posteriorly; intervals and interstices distinctly broader than punctures; second series of small punctures moderately dense only and less conspicuous than in previous species. Pubescence long, brown, with yellowish shade depending on illumination, of two distinct types: erect series on sides, slightly recumbent series on disc; erect series longer and denser; disc series shorter, sparse. Scutellum subtriangular, with few punctures and pubescence similar to surrounding area of elytra. Metathoracic wings well developed. Epipleura almost flat.

Ventral surface: punctation dense and 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 distinct. Metasternum minutely perforate at sides, with raised triangular, rugulose area behind 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 apically.

Legs: length less than half of body length. Tibia brown, lateral margins darker, curved, with pre-apical comb of spines; metatibia slightly longer than protibia and mesotibia; apex of mesotibia and metatibia slightly curved. Tarsi 5-5-5, dark yellow to light brown, paler towards the apex, about two-thirds of length of tibia; tarsomere length ratio ca. 1.2:1.0:1.0:1.0:2.9 (1.0-1.5: 0.8-1.0: 0.8-1.0: 0.8-1.0: 2.7-3.3); tarsomere 1 brown, with parallel margins, widest towards the apex, with dense comb of setae; tarsomeres 2-4 almost globular, outer edge with long yellow spiny setae on both sides, remaining portions with sparse minute setae; tarsomere 5 more yellow than brown, widest towards the apex, with at least three pairs of long robust spiny setae. Tarsal claws long, narrow, symmetrical.

Male genitalia: (Figs 6 , 7 ) length 0.58 mm (0.57-0.59 mm), width 0.14 mm (0.12-0.17 mm), stout, strongly sclerotised; median lobe more exposed in ventral view than dorsal view. Median lobe of aedeagus a bit shorter than parameres, symmetrical, broad, non-planar, varying in dorsal and ventral views; on dorsal view, apex acuminate, significantly and abruptly convexly widened mediad, middle portion wide; on ventral view, median lobe with an additional, slightly more slender, subcordiform lobe, reaching apical 0.3 where it terminates deeply emarginate. Parameres symmetrical, with outer face irregularly outlined and uneven texture near apex; apices dorsally broad; apices obliquely rounded; inner margins dorsally very slightly concave, almost unevenly sub-parallel; not distinctly convergent basally, forming a U-shape extending one-fourth the length of genitalia; ventrally only half as wide as in dorsal view, opening wider and exposing the entire width of median lobe, converging basally to form a deep “V”. Basal lobe asymmetrical, with strongly sclerotised basal margins. Ventrite VIII U-shaped, with narrow apical membranous lamina. Spiculum prominent.

Female genitalia: ovipositor relatively short (0.50-0.56 mm long), straight.

Differential diagnosis.

In the ovoid shape, the new species resembles B. vestitus (Sharp, 1902), B. maculatus Wooldridge, 1987 and B. magnus Wooldridge, 1987. Compared to other Philippine species, the range of size overlaps with B. punctatus and B. tarawakanus . The new species is remarkably different from these two in the smaller posterolateral angle (ca. 50°) of the pronotum in B. villarini sp. nov. compared to B. punctatus and B. tarawakanus , as well as B. negrosensis sp. nov. (75-80°). In addition to the posterolateral angle measure of pronotum, B. villarini sp. nov. is notably different from B. negrosensis sp. nov. in the length of tarsomere 5. Tarsomere 5 of B. villarini sp. nov. is as long as tarsomeres 2-4, while tarsomere 5 of B. negrosensis sp. nov. is almost as long as tarsomeres 1-4. Additionally, erect series of elytral pubescence is present on the posterior end of both species, but covers the distal one-third only of elytra in B. villarini sp. nov., while covering the distal one-half in B. negrosensis sp. nov.

Males of B. villarini sp. nov. are easily recognisable because the parameres are dorsally fused forming a rather shallow “U” (Fig. 6 ), not a “V” as in B. negrosensis sp. nov. (Fig. 4 ). This U-shaped opening separating the parameres extends only one-fourth the length of the aedeagus, while the opening spans at least half of the aedeagus for other Philippine species, such as B. ferax , B. punctatus and B. tarawakanus . The median lobe of the aedeagus resembles that of B. tarawakanus in terms of shape and height of the parameres. However, the median lobe of B. villarini sp. nov. is stouter and wider towards the middle portion.

B. villarini sp. nov. varies by 5.8% mean genetic distance (723 bp COI-3 ' mtDNA barcode) from an unidentified, but presumably closely-related Malaysian species and by at least 13.4% from any other Philippine congeners with available barcodes (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.

Etymology.

The new species is named and dedicated to the immediate past president of the Ateneo de Manila University, Fr Jose Ramon T. Villarin, SJ, PhD, who finished his term last year. During his reign for the past decade, Fr Villarin showed ardent support for research activities on the environment and sustainability. He is also a member of the Intergovernmental Panel on Climate Change which was conferred the 2007 Nobel Peace Prize for their study and recommendations on counteracting the global climate crisis.

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.