Genus Byrsax Pascoe, 1860 (Coleoptera: Tenebrionidae) In The Solomon Islands And New Guinea With Description Of A New Species Author Telnov, Dmitry Corresponding author: Dmitry Telnov. Department of Life Sciences, Natural History Museum, SW 7 5 BD, London, United Kingdom, E-mail: anthicus @ gmail. com. Coleopterological Research Center, Institute of Life Sciences and Technology, Daugavpils University, Vienības Str. 13, LV- 5401, Daugavpils, Latvia. Institute of Biology, University of Latvia, O. Vācieša Str. 4, LV- 1004, Rīga, Latvia. ORCID: 0000 - 0003 - 3412 - 0089 text Acta Biologica Universitatis Daugavpiliensis 2023 2023-12-30 23 2 163 172 https://du.lv/en/research/institutes/institute-of-life-sciences-and-technologies/issued-journal/acta-biologica-universitatis-daugavpiliensis/acta-biologica-universitatis-daugavpiliensis-archives/acta-biologica-universitatis-daugavpiliensis-volume-23-no-2-2023/genus-byrsax-pascoe-1860-coleoptera-tenebrionidae-in-the-solomon-islands-and-new-guinea-with-description-of-a-new-species/ journal article 10.59893/abud.23(2).004 1407-8953 12650065 Byrsax crypticus sp. nov. ( Figs. 3 , 6C‒E ) urn:lsid:zoobank.org:act: 003FB483-12F1- 4671-9210-0D9E3A5ABBC5 Buck (1958: 116) record ‘Niupani’ (Rennell Is.), as Byrsax tuberculatus Gravely. Kaszab (1980: 40) identification corrected to B. biroi . Type material designated. Holotype ♂ [ BHMN ] ( Fig. 3 ): SOLOMON IS. Rennell I. Niupani. 22.xi.1953 . J.D.Bradley. [printed] // RENNELL I. Expedition. B.M.1954-222. [printed] // Byrsax tuberculatus Grav. [handwritten] Det. F. D. Buck [printed] // Byrsax biroi Kasz. [handwritten] Dr Z. Kaszab det., 19 [printed] 96 [handwritten] [antennomeres 4–11 of the left antenna missing; the left hind leg detached from the specimen, glued on the same card near the specimen]. 166 Description. Holotype ♂ ( Figs. 3 , 6C‒E ). Dorsum dark brown, venter and expanded lateral margins of pronotum and elytra reddish brown. Maxillary and labial palpi and antenna pale yellowish brown. Legs pale brown. Body shortly subcylindrical, strongly convex in dorsal aspect, subopaque on forebody, opaque on elytra and venter. Head strongly transverse, retracted to pronotum up to posterior margin of compound eye, flattened on frons in dorsal aspect. Mandible apex strongly, acutely bidentate. Anterior margin of labrum emarginate. Distinct but fine, strongly arched groove at place of frontoclypeal suture. Clypeus impunctate, with a long paired slightly curved, dorso-posteriad pointing process (‘horn’) just inwards of supraocular plica (‘ridge’ of authors). Length of clypeal process about 1 mm . Anterior, external, and posterior margin of a process irregularly denticulate, inner margin transversely rugulose. A narrow gap present between ‘horn’ and supraocular plica. Supraocular plica short, touching upper margin of compound eye. Gena flattened in dorso-ventral aspect, produced laterad in front of Genus Byrsax Pascoe, 1860 ( Coleoptera : Tenebrionidae ) in the Solomon Islands and New Guinea with description of a new species compound eye. Genal canthus strongly protruding from lateral outline of head, partially concealing basal antennomere, irregularly sinuous in dorsal and lateral view, extending towards somewhat beyond midlength of an eye. Frons between eyes flattened, irregularly punctate, intervening spaces slightly glossy. Vertex strongly, irregularly corrugate, opaque. Compound eye asymmetrically elliptical, slightly protruding from lateral and dorsal outline of head, anterior margin subtruncate, posterior and dorsal margin rounded. Dorsal cranial setae inconspicuous, short and sparse, pale rufous, leaving large areas of head glabrous. Also processes sparsely covered with short setae. Antenna moderately long, clavate. Basal antennomere about 2.3‒2.4× as long as antennomere 2. Antennomere 2 shortened. Antennomere 3 with small median lateral angulation, about twice as long as antennomere 2. Antennomeres 4‒10 strongly serrate and asymmetrical, each with large, acutely angulate median lateral lobe, lobes of antennomeres 6‒10 longer than corresponding antennomere. Terminal antennomere asymmetrical, apically broadly rounded, flattened dorso-ventrally, about twice as long as penultimate and about as long as combined length of two preceding antennomeres. Terminal maxillary palpomere fusiform, tapered apically. Terminal labial palpomere fusiform, tapered apically. Pronotum widest across midlength, strongly transverse, subopaque, median area of pronotal disc convex in dorsal aspect, gently sloping laterad towards expanded, flattened and strongly deplanated lateral margin. Anterior margin broadly emarginate, posterior margin irregularly rounded, shallowly emarginate at posterolateral denticle (representing posterolateral angle of pronotum). Median area of pronotal disc with irregular vertical conical tubercles leaving narrow median line smooth. Dense irregularly circular punctures between tubercles, intervening spaces generally narrower than punctures, subopaque. Deplanate lateral area of pronotum with subvertical conical tubercles (five large, two minute or absent), intervening spaces impunctured, dorsum between tubercles opaque. Lateral margin of explanate lateral area of pronotum with about 11 denticles, two anterior of which bicuspidate. Moderately deep, short emargination on lateral margin of pronotum beyond to two anterior denticles. Deep and rather broad posterolateral slit at posterior margin of pronotum between moderately long posterolateral tubercle and expanded lateral margin. Dorsal pronotal setae very inconspicuous, sparse, short and curved, observed on lateral area of pronotal disc. Scutellar shield broadly triangular, apically pointed, dorsally punctured-corrugated. Elytra hardly longer than wide, strongly convex in dorsal aspect, nearly parallel-sided, laterally strongly declivous, flattened and modified into narrow expanded and deplanated lateral margin. Anterior margin of elytron with vertical tubercle in front of tuberculate anterolateral angle. Humeral callosity distinctly convex, multituberculate. Suture not raised. Elytral disc with series of irregular ventral conical tubercles of variable size and height. Some tubercles merging into short longitudinal plicae (especially postscutellar, either side of suture). Tubercles becoming distinctly smaller on declivous, lateral part of elytron and are sparse on expanded lateral area of elytron. Elytral punctures much larger and deeper than those on pronotum, arranged into nine rather regular longitudinal rows on each elytron, in part confused or interrupted by tuberculate structures. Intervening spaces between punctures and tubercles smooth. Intervals between punctures in rows narrower than punctures. Lateral margin of elytron regularly denticulate, denticles rounded apically. Elytral setae as those on pronotum, sparse across whole elytral disc and lateral sides. Epipleuron complete, very broad except at elytral apex, moderately densely punctate and sparsely setose. Metathoracic wings fully developed (functional). Legs moderately long. Femur glossy, shortly setose on ventral part. Tibia moderately glossy, with dense, short, whitish setae, tricarinate (median carina incomplete). Male basal metatarsomere strongly shortened, about as long as second metatarsomere. Terminal tarsomere of each leg thickened, slightly arched, distinctly longer than combined length 167 Dmitry Telnov of remaining tarsomeres. Pretarsal claws with short empodium. Male last visible tergite and sternite broadly rounded at posterior margin. Aedeagus as in Fig. 6C‒E , apicale about same long as basale. Sexual dimorphism. Female ( Fig. 4 ) smaller and less strongly convex, head without processes. Ecology. Occurs in lowland rainforests. Distribution. So far reliably known from Rennell Island, Rennell and Bellona Province , Solomon Islands . The distribution to include Choiseul Island would the identification of the studied female confirmed. Note. The female from Choiseul ( Fig. 4 ) with antennomere 4 strongly lobate (antennomeres 4‒10 strongly serrate) but no male from the same locality is available to confirm the yet tentative identification. Figure 4. Byrsax cf. crypticus sp. nov. , additional ♀ from Choiseul Island, dorsal view. D. Telnov. Differential diagnosis. The new species appears similar to Byrsax biroi (eastern New Guinea and Bismarck Archipelago ) but differs in the strongly lobate male and female antennomere 4, and in the shape of the aedeagus (the length ratio of the basale to apicale about 1 versus 1.45 in B. biroi ). Byrsax similaris Ando et Yamasako, 2013 (North Sulawesi) has the posterolateral slit of pronotum significantly narrower compared to that in the new species, the antennomere four is not lobate and the antennomere five slightly lobate in this species. Figure 5. Byrsax pinnaticollis Carter, 1914 , ♂ from Guadalcanal Island. A: dorsal view, B: lateral view, C: frontal view, D: dorso-lateral view. Images: D. Telnov [not to scale]. 168