Melolontha lachungensis 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 : 199-200

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

( Figs. 4 , 16 , 43 , 33–40 , 44 , 56 )

Type locality. India, Sikkim, North Sikkim, Lachung Forest .

Type material. Holotype, male, labelled: “ India, Sikkim, North Sikkim, Lachung Forest , 27°18' 10.728''N, 88°33'36.864''E, 20.iv.1992, leg. R.S. Mridha ” [ NZSI] . Paratypes: 2 males with same data as holotype [ NZSI] .

Description of holotype. Body length 23.3 mm, maximum body width 12.62 mm.

Colour ( Fig. 4 ). Pronotum, scutellum, venter, and legs reddish - brown; elytra light olive - green.

Head ( Figs. 33–34 ). Clypeus rectangular, apical angles rounded, slightly widened at apex; apical portion perpendicularly reflexed, moderately sinuate in frontal view; slightly convex 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 strongly concave, surface sparsely 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, 3.65 times as long as stem, antennomere 1 distinctly swollen apically, apical segment moderately elongate; labrum symmetrically bilobed, lobes transversally developed; mentum slightly concave centrally, surface glabrous with only a few scattered setae; maxillary palpi with apical palpomere subequal in length to combination of palpomeres 2–3; ocular canthus densely covered with brownish erect and robust setae.

Pronotum ( Fig. 35 ). Transverse, wid est in middle; basomedially protuberant posteriorly; surface densely to confluently punctate along lateral margin; puncture with a tiny, brownish seta; setae longer and more robust towards the centre; centre of pronotal disc sparsely punctate, punctures moderately large; sides of midline setose with spots consisting of concentrated brownish setae at apical sides of midline; setae dense along basomedial margin; serration of lateral margin poorly developed anteriorly, basal half of margin with completed bead.

Scutellar plate ( Fig. 36 ). Oval, surface lightly, sparsely punctate, glabrous; apical margin with a row of slender hair - like setae.

Elytra ( Fig. 4 ). 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 visible; outer margin of costa 1 with aligned row of whitish and scale - like setae; intervals rugose, intermixed with 2 types of whitish setae, lanceolate and scale - like (slender and smaller), both moderately densely distributed; 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, but tiny setae; epipleuron entirely setose, whitish-brown setae becoming gradually denser apically, posterior one third in a band; humeral umbone moderately swollen.

Pygidium ( Fig. 16 ). 1.52 times broader in width than length; anterior half with long, hair - like setae, remainder Triangular, intermixed with yellowish - white, scale - like setae; disc on either side slightly depressed medially; surface densely covered with whitish-brown, short setae; setae denser in apical portion; apex broadly rounded; lateral sides slightly curved.

Venter ( Fig. 38 ). Mesometasternal process weakly produced beyond mesocoxae, surface smooth with few hairs; meso- and metasternum with thick and dense hairs.

Abdominal sternites ( Fig. 40 ). Sternite 1–5 with a lateral maculation consisting of yellowish-brown, scale-like setae; maculation on sternite 6 distinctly present; abdominal surface moderately setose; setae small, whitish–brown to yellowish-brown, lanceolate and becoming slender medially, transversely distributed with scattered, longer setae in line; sternites 2–5 weakly fused medially; suture well defined.

Legs ( Figs. 37, 39 ) Protibiae unidentate, apical tooth acute ( Fig. 37 ); 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, posterior femur stouter, with shorter setae; apical portion of metatarsomere 1 distinctly swollen; outer metatibial spur subequal in length to combined length of metatarsomeres 1 and 2 ( Fig 39 ). Tibiae and tarsi moderately clothed with pale–white, scale–like, short setae at dorsal surface; meso- and metatibiae with 2 elongate apical spurs; mesotibial spurs slightly shorter than length of mesotarsomere 1.

Parameres ( Figs. 44 , 56 ). Symmetrical; basal piece subequal in length to paramere; lobes of parameres nearly rounded at apex, not pointed at end in dorsal view ( Fig. 44 ), more or less straight in lateral view ( Fig. 56 ); ventroapical process of paramere distinctly elongate and gradually acuminate with a strong, crest-like protuberance on top of right paramere in lateral view ( Fig. 56 ); dorsal process marked and protuberant ( Fig. 44 ).

Female unknown.

Collecting circumstances. At light.

Differential diagnosis. Melolontha lachungensis new species differs from the other two species in the group ( M. phupanensis and M. arunachalensis new species) by the unique structure and shape of the parameres and unidentate protibiae. See species key and Table 1 to distinguish it from M. phupanensis and M. arunachalensis new species. The newly described species also shows similarities 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. lachungensis new species). Melolontha tenuicauda has a much shorter antennal club, as compared to M. lachungensis new species.

Etymology. The name (adjective in the nominative singular) refers to the type locality, Sikkim.

Distribution. So far, only known from the type locality: India, Sikkim ( 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 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 33–40. Melolontha lachungensis new species (holotype). 33, head and antennae; 34, basal segments of antennae; 35, pronotum; 36, scutellar plate; 37, protibia; 38, mesometasternal process; 39, metatarsomeres; 40, abdomen.

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.