Amphicrossus brunneus Dagupta and Pal, 2019

Dasgupta, Jhikmik & Pal, Tarun Kumar, 2019, Three New Species of Amphicrossus Erichson, 1843 (Coleoptera: Nitidulidae: Amphicrossinae) from Northeast India, with a Review of the Genus in the Region, The Coleopterists Bulletin 73 (2), pp. 307-320 : 314-317

3. Amphicrossus brunneus Dagupta and Pal , new species

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Type Material. Holotype male, genitalia dissected and mounted on cover slip and pinned with the holotype. Original label: “ INDIA: Arunachal Pradesh, Tirap Dist. [presently Changlang dist.], Zero Camp, 27.7422° N, 96.6424° E, 1 ex., 20.xii.1983, S. Biswas and party leg.” . Paratype: 1 Ƌ, same data as holotype.

Description. Oval, globose, ventrally subdepressed, color testaceous to dark brown, dorsum finely punctate ( Fig. 25 ); cuticle with moderately dense, long, golden, decumbent pubescence; elytra bearing a pair of dense, erect setal clusters near and slightly above midpoint of elytral suture. Head: Transverse, about 1.1X as broad as long, frons depressed; punctures on frons and vertex round and moderately deep, about size of an eye facet, separated from each other by 1–2 puncture diameters; eyes moderately large and moderately projected, about 0.4X as long as head, outer margin rounded, somewhat finely facetted; temple indistinct; golden yellow setae present on frons and vertex. Antenna about 1.2X as long as head; antennal club about 1.3X as long as broad, club segments compact, about 0.3X as long as antenna. Pronotum: Transverse (LP: WP = l.0:1.8), anterior margin broadly emarginated; lateral margins arcuate, posterior margin bisinuate, anterior angles sharply obtuse, posterior angles broadly rounded, lateral margins bordered with a dense row of moderately long cilia about half length of eye. Rather convex ( Fig. 30 ), surface distinctly punctate, punctures about as large as those on vertex, separated by 1–2 puncture diameters; moderately dense, decumbent setae on disc. Scutellum: Transverse, about 1.6X as broad as long, triangular and somewhat arched laterally; punctures round, about size of an eye facet, separated by 1–2 puncture diameters; small, fine, golden setae visible. Elytra: About 1.2X as broad as long, anterior margin closely fit with posterior margin of pronotum, humeral angles nearly right-angled, sides arcuate, borders explanate, apices truncate ( Figs. 33, 36 ); punctures round, about size of an eye facet, separated by 1–2 puncture diameters; setae fine and moderately long, decumbent. Abdominal tergites: Partially covered by elytra, exposed part of abdomen 1.8X as broad as long. Venter: Uniformly reddish brown ( Fig. 26 ). Prosternal process with rounded apex, reaching to mesoventrite. Metaventrite densely pubescent. Abdominal ventrite ( Fig. 42 ) with hypopygidium partially protruding, apex truncate, and accommodated within bisinuate margin of preceding abdominal segment. Pygidium ( Fig. 39 ) with medially emarginated apex, short setae present on postero-lateral sides of apex. Aedeagus: Broadly elongate, membranous median lobe with subparallel sides and a single median strut; tegmen with paired leg-like parameres, slightly robust near posterior 2/3 and gradually narrowing apicad, tuft of long setae arising 1/4 distance from apices of parameres, tegminal struts arising from basal extremity of each paramere and fusing anteriorly ( Figs. 48, 51 , 55–56 ). In lateral view, parameres gradually narrow from base to apex; apex round, a tuft of setae arising from the ventral margin of the parameres.

Measurements. TL = 4.37–4.63 mm; WH = 0.83–0.84 mm; LA = 0.93–0.95 mm; LP = 1.49– 1.53 mm; WP = 2.75–2.76 mm; LE = 2.43–2.48 mm; WE = 2.92–3.05 mm.

Etymology. The species name is derived from the Latin word ‘ brunneus ’ meaning brown referring to the color of its integument.

Distribution. INDIA: Arunachal Pradesh.

Comparative Notes. The species resembles Amphicrossus nebulosus Kirejtshuk, 2005 in the shape and position of the tuft of setae on the dorsal

surface of the elytra, the shape of the last abdominal ventrite and hypopygidium, and shape of the male genitalia, but can be differentiated from the latter by the medially indented pygidial apex ( Fig. 39 ) with dense setae and parameres distinctly broadened in the middle in the dorsal view ( Fig. 51 ) (vs. pygidial apex rounded and parameres subparallel in dorsal view in A. nebulosus ). The species is also similar to A. discolor in the structure of the male genitalia, but can be differentiated from the latter by the stout and somewhat longer tuft of erect setae on the elytra

55–56) A. brunneus ; 57–58) A. adustipennis ; 59–60) A. discolor .

( Fig. 36 ) that points anteriorly in lateral view, the hypopygidium ( Fig. 42 ) distinctly protruding from the middle of the last abdominal ventrite, the emarginated pygidial apex with dense setae, the inner margin of the anal sclerite reaching the apex ( Fig. 45 ), and the parameres somewhat broadened in the middle in dorsal view (vs. a shorter and thinner tuft of setae on the elytra that points posteriorly ( Fig. 32 ), hypopygidium ( Fig. 41 ) rather transverse and small, pygidial apex rounded with tiny setae ( Fig. 38 ), inner margin of the anal sclerite not reaching the apex ( Fig. 44 ) and subparallel parameres in dorsal view ( Fig. 50 ) in A. discolor ).

Figures

Figs. 21–28. Amphicrossus species in Northeast India. 21–22) A. discolor, dorsal and ventral views, respectively; 23–24) A. kabitae, dorsal and ventral views, respectively; 25–26) A. brunneus, dorsal and ventral views, respectively; 27) A. adustipennis, dorsal view; 28) A. densatus, dorsal view (photograph by Andrew Cline).

Figs. 29–46. Amphicrossus species. Pronota: 29) A. discolor; 30) A. brunneus; 31) A. adustipennis. Right elytron, dorsal view: 32) A. discolor; 33) A. brunneus; 34) A. adustipennis. Elytron, lateral view: 35) A. discolor; 36) A. brunneus; 37) A. adustipennis. Pygidium: 38) A. discolor; 39) A. brunneus; 40) A. adustipennis. Last abdominal ventrite: 41) A. discolor; 42) A. brunneus; 43) A. adustipennis. Anal sclerite: 44) A. discolor; 45) A. brunneus; 46) A. adustipennis.

Figs. 47–52. Amphicrossus species, male genitalia. 47) A. discolor, lateral view; 48) A. brunneus, lateral view; 49) A. adustipennis, lateral view; 50) A. discolor, ventral view; 51) A. brunneus, ventral view; 52) A. adustipennis, ventral view.

Figs. 53–60. Amphicrossus species, male genitalia, lateral and ventral views, respectively. 53–54) A. kabitae;