Aethina (Aethina) nigrocastanea Grouvelle, 1903

Dasgupta, Jhikmik & Pal, Tarun Kumar, 2022, On Aethina Erichson of Northeast India (Coleoptera: Nitidulidae: Nitidulinae), Zootaxa 5124 (5), pp. 533-550 : 541

Aethina (Aethina) nigrocastanea Grouvelle, 1903 ; stat. rev.

Aethina nigrocastanea Grouvelle, 1903: 115 ; Grouvelle, 1908: 380.

Note: This species, synonymised with Aethina vicina Grouvelle, 1894 by Kirejtshuk 1986, is re-estabished here as a distinct species.

Diagnosis: Body ( Figs. 36, 37 ) oval, dorsal surface rather convex and ventral surface somewhat flattened, chocolate brown, densely pubescent. Pronotum and elytra bordered. Dorsum covered with dense, moderately long, golden, semi-erect setae.

Head transverse, about as broad as long, frons feebly depressed; punctation on frons round, distinct, diameter about 2× the size of the eye facets, separated by about 0.75–1 diameter of punctures; punctures on vertex coarse, round and deep, about 4× the size of eye facets, separated by about 0.5–0.75 diameter of punctures; setae on frons and vertex moderately long, dense and decumbent; eyes large and moderately projected, about 0.4× as long as head, outer margin rounded, finely facetted. Antenna about 1.4× as long as head; antennal club about 1.5× as long as broad, about 0.3× as long as antenna.

Prothorax transverse (l.0: 1.7), anterior margin distinctly arcuate; sides arcuate, posterior margin bisinuate, anterior angle acute, posterior angle somewhat pointed. Pronotum somewhat convex, surface distinctly punctate, separated on top of pronotal disc by 0.5–1 diameter; moderately long, semi-erect setae present on disc.

Scutellar shield transverse, about 1.7× as broad as long, semi-circular in shape with rounded apex; punctures slightly finer than those on pronotum, separated by 0.75–1 diameter of punctures, setae moderately long, golden, semi-erect, posteriorly directed.

Elytra together about 1.1× as broad as long, anterior margin closely fitting with hind margin of prothorax, humeral angles right-angled, sides uniformly arcuate, apices separately rounded; punctures somewhat oval, shallow and indistinct, scattered, slightly longer than those on pronotum; setae moderately long, semi-erect with the surface and posteriorly directed.

Exposed portion of abdominal tergites about 2× as broad as long; setae moderately long, decumbent, posteriorly directed.

Ventral side reddish brown with head, prosternal process and metaventrite somewhat darker; gular region of head with subparallel antennal grooves running posterad. Mesocoxae bears a median longitudinal carina, mesocoxal lines reaching almost up to three-fourths of the length of the metaventral-metanepisternal suture from base, thereby making a distinct axillary space.

Aedeagus ( Figs. 32, 33 ): Parameres elongated spoon-shaped with apex rounded, short setae present on the distal half of the length of lateral margin. Median lobe rectangular-shaped, somewhat elongate with truncate apex and a bifurcated flap extending beyond the apex.

Measurements (in mm): Total length 2.84, width of head across eyes 0.53, length of antenna 0.73, length and width of prothorax 1.03 and 1.77, length and width of elytra together 1.58 and 1.81.

Material examined: 1 ex. INDIA: E. Himalayas, West Bengal, Darjeeling Dist., Peshoke , 2000-3500 ft., 23.iv.1911 – 11.v.1915, F. H. Gravely Coll., Det. by A. Grouvelle .

Distribution. INDIA: West Bengal (Darjeeling).

Remarks. Aethina (Aethina) nigrocastanea Grouvelle, 1903 was synonymised with Aethina (Aethina) vicina Grouvelle, 1894 by Kirejtshuk (1986). Both the species are available in the reference collection of ZSI (identified by Grouvelle). We dissected out the male genitalia of the former species and compared it with the line diagram of the male genitalia of A. (A.) vicina Grouvelle, 1894 as given by Kirejtshuk, 1986. We arrived at a conclusion that although morphologically very similar, A. (A.) vicina differs from A. (A.) nigrocastanea in the body being blackish [vs. body chocolate-brown in A. (A.) nigrocastanea ], shape of tegmen of male genitalia with truncate apex [vs. tegmen of male genitalia with rounded apex in A. (A.) nigrocastanea ], shape of median lobe of male genitalia with pointed apex and bifid flap situated rather far from the apex [vs. median lobe of male genitalia with truncate apex and bifid flap extending beyond the apex in A. (A.) nigrocastanea ]. The specific status of A. (A.) nigrocastanea Grouvelle is therefore re-established.

Figures

FIGURES 25–39. Aethina (Circopes) subquadrata (Motschulsky, 1858): 25–29: 25, abdomen with pygidium, dorsal view, photograph; 26, male genitalia with tegmen and median lobe, microphotograph; 27, ovipositor, microphotograph; 28, male genitalia: tegmen, line drawing; 29, male genitalia: median lobe, line drawing; Aethina (Aethina) vicina Grouvelle, 1894: 30–31, 34–35: 30, male genitalia: tegmen, line drawing (derived from Kirejtshuk, 1986); 31, male genitalia: median lobe, line drawing (derived from Kirejtshuk, 1986); 34, dorsal habitus; 35, ventral habitus. Aethina (Aethina) nigrocastanea Grouvelle, 1903: 32–33, 36–39; 32, male genitalia: tegmen, line drawing; 33, male genitalia: median lobe, line drawing; 36, ventral habitus, photograph; 37, dorsal habitus; 38, male genitalia: tegmen, microphotograph; 39, male genitalia: median lobe, microphotograph.