Amphicrossus discolor Erichson, 1843

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 : 318

4. Amphicrossus discolor Erichson, 1843

Amphicrossus discolor Erichson 1843: 348 .

Material Examined. INDIA: Arunachal Pradesh, Namdapha Tiger Reserve , 27.4455° N, 96.5358° E, 08.iv.1981, S. Biswas, 1 ex. ; Uttarakhand, Dehradun, base of W. Himalaya , 30.3165° N, 78.0322° E, viii.1910, V. S. Iyer, Det. by Grouvelle as Amphicrossus opacus (Reg. No. 8607/ 18, 8608/18, 8611/18), 3 ex. ; Bengal, Madhupur (presently Jharkhand state), 22.6302° N, 87.0562° E, 18.x.1909, C. Paiva, Det. by Grouvelle as Amphicrossus oblongus Grouvelle (Reg. No. 3497/ 21) 1 ex. ; Bengal, Rajmahal (presently Jharkhand state), 25.0543° N, 87.8309° E, 06.vii.1909, Annandale, ex: rotten patch on living tree trunk, Det. by Grouvelle as A. discolor (Reg. No. 1289/16) 2 ex.

Description. Oval, globose, ventrally subdepressed, color chestnut-brown to dark brown, finely punctate dorsum ( Fig. 21 ); cuticle with moderately dense, long, golden, decumbent pubescence; elytra bearing a paired brush of dense, erect setal clusters near and slightly above the midpoint of the elytral suture. Head: Transverse, about 1.2X as broad as long, frons subdepressed; punctures on frons and vertex round and moderately deep, about size of an eye facet, separated by 1–2 puncture diameters; eyes moderately large and moderately projected, about 0.4X as long as head, outer margin rounded, finely facetted; temple indistinct; golden yellow setae present on frons and vertex. Antenna about 1.4X 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: 1.6), 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 1/4 as long as eye. Rather convex ( Fig. 29 ), surface distinctly punctate, punctures about as large as those on vertex of head, separated by 1–2 puncture diameters; moderately thick and dense, decumbent setae on disc. Scutellum: Transverse, triangular with sides somewhat arcuate; punctures round, about half size of an eye facet, separated by 2–3 puncture diameters; setae indistinct. Elytra: About 1.2X as broad as long, anterior margin closely fit with posterior margin of prothorax, humeral angles nearly right-angled, sides slightly arcuate, borders somewhat explanate, apices separately rounded ( Figs. 32, 35 ); 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 about 1.9X as broad as long. Pygidium ( Fig. 38 ) with rounded apex, short setae present on apical margin. Venter: Uniformly reddish brown ( Fig. 22 ). Prosternal process subparallel with apex rounded, reaching to mesoventrite. Metaventrite punctate-pubescent. Abdominal ventrite ( Fig. 41 ) with hypopygidium flat and accommodated within the sinuated margin of the preceding abdominal segment. Aedeagus: Broadly elongate, membranous median lobe with subparallel sides and a single median strut; tegmen with paired leg-like parameres, tuft of long setae arising 1/4 distance from apices of parameres, tegminal struts arising from basal extremity of each parameres ( Figs. 50 , 59–60 ). In lateral view ( Figs. 47 , 59 ), hook-like parameres gradually narrowing from base to apex, parameres distinctly sinuate near midpoint of dorsal surface, apex somewhat projected laterally, a tuft of setae arising from ventral margin of parameres.

Measurements. TL = 4.58–4.73 mm; WH = 0.78–0.79 mm; LA= 0.95–1.03 mm; LP = 1.49– 1.58 mm; WP = 2.53–2.61 mm; LE = 2.20–2.56 mm; WE = 2.68–2.84 mm.

Distribution. INDIA: Arunachal Pradesh [New State Record], Assam, Sikkim, Uttarakhand, Jharkhand [New State Record]; MYANMAR: Pegu; VIETNAM; TAIWAN; CHINA.

Remarks. The identity of this species was ascertained from a line drawing of the male genitalia of A. discolor sent by Dr. A. G. Kirejtshuk, Russian Academy of Sciences, St. Petersburg. The two specimens in the ZSI collection that were determined by A. Grouvelle as A. opacus and A. oblongus are conspecific, and their male genitalia conform with that of A. discolor (drawn by A. G. Kirejtshuk). Hence, the specimens are now redetermined as 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;