Melolontha arunachalensis Gupta, Keith, Bhunia, Das, Ghosh & Chandra, 2023

Gupta, Devanshu, Keith, Denis, Bhunia, Debika, Das, Priyanka, Ghosh, Joyjit & Chandra, Kailash, 2023, Review of Melolontha Fabricius, 1775 (Coleoptera: Scarabaeidae: Melolonthinae) from India with the description of two new species, Zootaxa 5263 (2), pp. 191-216 : 198-199

Melolontha arunachalensis Gupta, Keith, Bhunia, Das, Ghosh & Chandra , new species

( Figs. 3 , 15 , 25–32 , 43 , 55 )

Type locality. India, Arunachal Pradesh, Pange Valley .

Type material. Holotype, male, labelled: “ India, Arunachal Pradesh, Pange Valley , 27°13'15.024''N, 93°10'40.6128''E, 11.iv.2015, leg. K.A. Subramaniam ” [ NZSI] . Paratypes: 3 males with the same data as holotype [ NZSI] .

Description of the holotype. Body length: 28.15 mm; maximum body width 15.35 mm.

Colour. Pronotum, scutellum, venter, and legs dark brownish-black. Elytra reddish - brown. Setae whitishyellow.

Head ( Figs. 25–26 ). Clypeus rectangular, apical angles rounded, slightly widened apically, apex perpendicularly reflexed, moderately sinuate in frontal view, surface concave medially, lateral angles planar, surface densely and evenly punctate, punctures large, each bearing a short, robust, erect seta, setae light yellowish-brown; clypeofrontal suture complete; centre of frons concave, surface densely setose, side of eyes densely setose, setae moderately longer and more robust than those on clypeus; sides slightly narrowed making eyes larger. Antennae 10 segmented with 7 segmented club, lamellae strongly curved outwardly, 3.62 times as long as stem; antennomere 1 distinctly swollen apically, apical segment moderately elongate; labrum symmetrically bilobed, each lobe transversally developed; mentum slightly concave centrally, surface almost glabrous with only a few scattered setae; maxillary palpus with apical palpomere subequal in length to combination of palpomeres 2–3; ocular canthus heavily covered with brownish erect robust setae.

Pronotum ( Fig. 27 ). Transverse, widest at middle, basomedially slightly protuberant posteriorly; surface densely to confluently punctate along lateral margin; punctures moderately large with a tiny, brownish seta, setae longer and more robust towards centre; centre of pronotal disc sparsely punctate; sides of midline setose with spot consisting of concentrated brownish setae on each apical side of midline; setae denser along basomedial margin; serration of lateral margin distinctly developed, basal half of margin with completed bead.

Scutellar plate ( Fig. 28 ). Oval, surface lightly, sparsely punctate, two longitudinal rows of setae fused at point making a triangle, apical margin has a row of slender hair-like setae.

Elytra ( Fig. 3 ). Broadest at base. Costae 1–3 (costa one as sutural costa) glabrous and well developed, costae 2 and 3 broadly fused on apical umbone, costa 4 feebly developed and hardly observable; outer margin of costa 1 with aligned row of whitish, scale - like setae; intervals rugose, intermixed with two kinds of whitish setae, one lanceolate and scale - like and other slender and smaller, both moderately dense in distribution; posthumeral and 3 basal patches composed of overlapping, white, scale - like setae, posthumeral patch slender in shape; apical area of elytron steeply depressed below plane of disc, densely covered with whitish brown, tiny setae; epipleuron entirely setose, whitish brown setae evenly distributed; humeral umbone moderately swollen.

Pygidium ( Fig. 15 ). Triangular, 1.6 times wider than long; anterior half with long; disc either side slightly depressed medially; surface densely covered with whitish brown setae; setae short evenly distributed or moderately scattered along midline; apex rounded; lateral margin straight.

Venter ( Fig. 30 ). Mesometasternal process produced beyond mesocoxae, surface smooth with few hairs; meso- and metasternum with thick, dense hairs.

Abdominal sternites ( Fig. 32 ). Abdominal segments 1–5 with a lateral maculation of yellowish-brown, scalelike setae; maculation on sternite 6 light; abdominal surface densely setose; setae whitish brown to yellowish–brown, lanceolate, slender medially, transversely distributed with scattered, longer setae in line; sternites 2–5 weakly fused medially; suture well defined.

Legs ( Figs. 29, 31 ). Protibiae bidentate laterally, apical tooth acute ( Fig. 29 ); tarsal claws symmetrically unidentate, abruptly curved apically with a small, vertical tooth at base. Pro- and mesofemora transversely flattened, surface densely clothed with long, hair-like, brown setae; metafemur stout, with shorter setae; apical portion of first metatarsus distinctly swollen; outer metatibial spur subequal in length to combined length of metatarsomeres 1 and 2 ( Fig. 31 ); dorsal surface of tibiae and tarsi moderately clothed with pale white, scale-like, short robust setae; meso- and metatibiae with two elongate apical spurs; mesotibial spurs slightly shorter than length of mesotarsomere 1.

Parameres ( Figs. 43 , 55 ). Symmetrical; basal piece subequal in length to paramere; lobes of parameres nearly straight at apex, slightly pointed at ends in dorsal view ( Fig. 43 ), strongly curved, bent backwards at apex in lateral view ( Fig. 55 ); dorsal process, clearly marked, slightly produced ( Fig. 43 ), ventroapical process distinctly elongate and gradually acuminate apically with a small, crest-like protuberance on top of right paramere in lateral view ( Fig. 55 ).

Female unknown.

Collecting circumstances. At light.

Differential diagnosis. Melolontha arunachalensis new species differs from the other two species in the group ( M. phupanensis and M. lachungensis new species) by its unique structure and shape of the parameres. See species key and Table 1 to distinguish the newly described species from M. phupanensis and M. lachungensis new species. The newly described species is similar in general appearance to Melolontha costipennis Fairmaire, 1889 (= M. tricostata Brenske, 1903 ) and M. tenuicauda Fairmaire, 1896 , both of which are known from China (Tibet). Melolontha costipennis , placed under the aeneicollis group ( Li et al. 2010), differs from the new species by a narrowly elongated pygidium at the apex (pygidium rounded at apex, not elongated in M. arunachalensis new species). Melolontha tenuicauda has a much shorter antennal club, as compared to M. arunachalensis new species.

Etymology. The name (adjective in the nominative singular) refers to the Arunachal Pradesh state of India.

Distribution. So far, only known from the type locality: India, Arunachal Pradesh, Pange Valley ( Fig. 72 ).

Figures

FIGURE 72. Map of North-east India showing the type localities of the newly described species.

FIGURES 1–4. Habitus of Melolontha species. 1, M. guttigera; 2, M. virescens; 3, M. arunachalensis new species (holotype); 4, M. lachungensis new species (holotype).

FIGURES 13–18. Pygidium of Melolontha species. 13, M. guttigera; 14, M. virescens; 15, M. arunachalensis new species (holotype); 16, M. lachungensis new species (holotype); 17, M. aeneicollis; 18, M. cuprescens.

FIGURES 25–32. Melolontha arunachalensis new species (holotype). 25, head and antennae; 26, basal segments of antennae; 27, pronotum; 28, scutellar plate; 29, protibia; 30, mesometasternal process; 31, metatarsomeres; 32, abdomen.

FIGURES 41–46. Parameres of Melolontha species in dorsal view. 41, M. guttigera; 42, M. virescens; 43, M. arunachalensis new species (holotype); 44, M. lachungensis new species (holotype); 45, M. aeneicollis; 46, M. cuprescens.

FIGURES 53–64. Parameres of Melolontha species in lateral view. 53, M. guttigera; 54, M. virescens; 55, M. arunachalensis new species (holotype); 56, M. lachungensis new species (holotype); 57, M. aeneicollis; 58, M. cuprescens; 59, M. chinensis; 60, M. nepalensis; 61, M. carinata; 62, M. indica; 63, M. flabellata; 64, M. furcicauda.