Lepidotrigona sikkimensis Viraktamath, 2022

Viraktamath, Shashidhar & Thangjam, Rojeet, 2022, Description of four new species of Lepidotrigona (Hymenoptera: Apidae: Meliponini) from north-east India, Zootaxa 5175 (1), pp. 1-30 : 13-27

Lepidotrigona sikkimensis Viraktamath sp. n.

( Figs. 4d , 5d , 13 , 14 , 15 )

Diagnosis. Lepidotrigona sikkimensis belongs to the ventralis species group, with males and females measuring a mean of 4.71 and 4.16 mm in body length and 4.63 and 4.49 mm in forewing length, respectively ( Table 1 ). Male bees are distinct with mesoscutum without a border of scale-like plumose hairs ( Fig. 13 b ); anterior and posterior margins of hind tibia fringed with white hairs; reddish-brown first metasomal tergum with broad dark brown semicircular band ( Fig. 13 b ); apical margin of sternum 4 gently convex medially ( Fig. 15 a ); long (0.29 mm) apicosubmedian lobes on sternum 5 widely separated by 0.31 mm ( Fig. 15 b ); long (0.35 mm) triangular apicomedian lobe on sternum 6 with acutely pointed apex; apodemal lobes moderately separated ( Fig. 15 c ); very long penis valve (0.89 mm) and gonostylus (0.90 mm) ( Table 2 ).

Female bees are of moderate size (4.16 mm body length) with mesoscutum bordered with yellow scale-like hairs; wings blackish brown; first metasomal segment with a distinct dark brown semi-circular band; malar space length is short (0.10 mm).

Description

Males

Coloration. Head, mesosoma, metasoma black ( Fig. 13 a ); labrum reddish-brown; scape black, pedicel, flagellar segments dark reddish-brown approaching to black; ocelli transparent pale to white; compound eyes black, but in some yellowish to reddish-brown ( Fig.13 c ); Legs dark reddish-brown except for tibiae, tarsi light brown. Tegulae dark reddishbrown; wings with brownish tinge; pterostigma, veins light brown. Mesoscutum with three very narrow, shiny longitudinal stripes arising from the anteromedial margin, extending up to the middle of mesoscutum. Metasomal tergum 1 pale with the reddish-brown broad semi-circular band ( Fig. 13 b ); remaining terga with various shades of reddish-brown; the last tergum lighter; in some males, all terga black and semi-circular band on first tergum indistinct; sterna light brown with dark brown bands ( Fig. 13 a ).

Pilosity. Clypeus, face with white fine plumose hairs ( Fig.13 c ); vertex, occiput with long white erect hairs; lower part of occiput with a patch of very fine white hairs; post-gena with long white hairs ( Fig. 13 a ). Mesoscutum without scale-like hairs but integument clothed with short pale hairs; mesoscutellum fringed with pale long hairs ( Fig. 13 b ). Anterior, the posterior and upper surface of the hind tibia with white hairs. Pronotal lobe, mesepisternum and metepisternum clothed with yellowish long plumose hairs with higher density at the lower side; anterolateral parts of propodeum with short, yellowish plumose hairs ( Fig. 13 a ). Metasomal terga with fine short hairs being denser and longer on terminal terga; sterna with dense white fine hairs.

Morphometry. Males measure a mean of 4.71 mm in body length with head width 1.77 mm and head length 1.23 mm ( Table 1 ); eye 1.14 mm long, 0.48 mm wide; upper interocular distance 1.05 mm while interocellar and ocellocular distance 0.39 and 0.20 mm, respectively; scape 3.40× longer than its width (0.15 mm); mandible 2.26× longer than its width (0.19 mm); forewing 4.63 mm long, 1.49 mm wide while wing diagonal length 1.27 mm; hind tibia and hind basitarsus 1.41 and 0.55 mm long, respectively.

The ratio of head length and width 0.69; eye length to upper interocular distance 1.09; interocellar to ocellocular distance 1.95; forewing length to width 3.11; hind tibial length to forewing diagonal length 1.11; hind basitarsus width to hind tibial width 0.66 ( Table 3 ).

Metasomal sterna and genitalia. The following description is based on dissection of four males. Gradulus of sternum 4 touches the antecosta briefly; apical margin gently convex medially, sinuate on each lateral side ( Fig. 15 a ). In sternum 5, the gradulus in touch with antecosta extensively; apicosubmedian lobes narrow, pointed, 0.29 mm long terminating into 2 to 4 short spines; both lobes separated widely by 0.31 mm distance with a broad inverted U-shaped concavity; each apicolateral lobe longer than wide (0.15 mm long, 0.10 mm wide), with broad rounded apex ( Fig. 15 b ). In sternum 6, the antecosta gently convex medially, apicomedian lobe 0.35 mm long with acutely pointed apex; the apodemal lobes moderately separated from each other ( Fig. 15 c ).

Genitalia asymmetrical except gonostyli, well sclerotized ( Fig. 15 d ). Left gonocoxa larger (0.21 mm long, 0.50 mm wide) than the right gonocoxa (0.24 mm long, 0.39 mm wide) ( Table 2 ); penis valve 0.89 mm long with a basal width of 0.35 mm; terminal half of each penis valve very slender, curved differently, often on one side thus overlapping on each other with pointed apex. Gonostyli symmetrical, tubular, 0.90 mm long with a width of 0.04, 0.06 and 0.07 mm at the base, middle and terminal expanded part, respectively ( Fig. 15 d ); gently sinuate at the mid-length; the medial and lateral surface of the expanded part lined with series of very long and short setae with density increasing towards apex ( Fig. 15 e ).

Females

Coloration. Head black; labrum dark reddish-brown to black; scape dark reddish-brown to black except for basal bulb ochraceous; flagellar segments dark reddish-brown; ocelli pale; compound eyes light brown to dark brown ( Fig. 14 a-c). Mesosoma, tegula black; wings blackish brown; pterostigma, veins brown. Mesoscutum with three very narrow, shiny longitudinal stripes arising from the anteromedial margin, extending up to the middle of mesoscutum. Metasomal first tergum pale with the distinct dark brown semi-circular band; remaining terga black ( Fig. 14 b ); in some, metasomal terga light brown except the terminal terga yellowish brown to dark brown; sterna ochraceous.

Pilosity. Clypeus, entire face with fine plumose hairs ( Fig. 14 c ); vertex, occiput with long greyish erect hairs; gena, post gena, the lower part of occiput with patches of fine white hairs ( Fig. 14 a ). Mesoscutum bordered by yellow scale-like hairs; mesoscutellar margin fringed with long yellow hairs ( Fig. 14 b ); pronotal lobe, mesepisternum, metepisternum, anterolateral areas of propodeum with dense plumose yellowish hairs ( Fig. 14 a ). Anterior margin of the hind tibia with yellow setae, posterior margin with yellow intermixed with dark brown setae, upper surface covered with sparse yellow setae. Metasomal terga with fine yellowish hairs with higher density towards terminal segments; terminal terga fringed with long yellowish hairs; sterna with dense yellow hairs with density progressively increasing towards terminal sterna.

Morphometry. Females measure a mean body length of 4.16 mm while the head length and width 1.29 and 1.83 mm, respectively ( Table 1 ); eye 1.11 mm long, 0.39 mm wide; upper interocular distance 1.19 mm while interocellar and ocellocular distance 0.35 and 0.30 mm, respectively; median ocellus 1.50× greater than malar space length (0.10 mm); scape 0.65 mm long 0.10 mm wide; mandible 2.52× longer than its width (0.27 mm) while the forewing 2.90× longer than its width (1.55 mm); wing diagonal length 1.23 mm; hind tibia 1.47 mm long, 0.56 mm wide while the hind basitarsus 0.64 mm long, 0.36 mm wide.

The ratio of head length to width 0.71; scape length to eye length 0.59; forewing length to width 2.88; hind tibial length to head width 0.82; hind tibial length to forewing diagonal length 1.20; hind basitarsus width to hind tibial width 0.63 ( Table 3 ).

Materials examined. Holotype: Male: Sikkim: Mamley (27.1907° N, 88.3726° E), 09. xii. 2017, leg. S. Viraktamath, deposited at UASB . Paratypes: Eight males, 70 females with the same collection data deposited at UASB ; one female paratype will be deposited at ZSIK .

Etymology. The species name is derived based on the name of the state “ Sikkim ” where this species was collected.

Figures

FIGURE 4. Comparison of metasomal sterna 4 (s-4), 5 (s-5) and 6 (s-6) of Lepidotrigona thenzawlensis (a), L. rajithae (b), L. amruthae (c) and L. sikkimensis (d) (Not to scale)

FIGURE 5. Comparison of genitalia dorsal view (1), seen from above (2), terminal expanded part of gonostylus (3) of Lepidotrigona thenzawlensis (a), L. rajithae (b), L. amruthae (c) and L. sikkimensis (d) (Not to scale)

FIGURE 13. Lepidotrigona sikkimensis n. sp. Male holotype: a. lateral habitus, b. head, mesosoma and basal part of metasoma dorsal view, c. head frontal view

FIGURE 14. Lepidotrigona sikkimensis n. sp. Female paratype: a. lateral habitus, b. head, mesosoma and basal part of metasoma dorsal view, c. head frontal view

FIGURE 15. Lepidotrigona sikkimensis n. sp. Male paratype: a. Metasomal sternum 4, b. sternum 5, c. sternum 6, d. genitalia, e. gonostylus terminal part