Lepidotrigona rajithae Viraktamath and Rojeet, 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 : 10-12

Lepidotrigona rajithae Viraktamath and Rojeet sp. n.

( Figs.4 b , 5 b , 6 c, d , 7 , 8 , 9 )

Diagnosis. Lepidotrigona rajithae is characterized by large males (mean body length 6.00 mm, range 5.80 to 6.40 mm) and long forewings (mean 4.78 mm, range 4.70 to 5.05 mm); extremely short malar space length (0.01 mm); very broad semi-circular brown band on the metasomal first segment ( Fig. 7 b ); apical margin of sternum 4 weakly emarginate medially, bisinuate laterally ( Fig. 9 a ); apicosubmedian lobes of sternum 5 separated by a short distance of 0.18 mm ( Fig. 9 b ); apicomedian lobe of sternum 6, 0.32 mm long and bluntly rounded at the apex ( Fig. 9 c ); apodemal lobes moderately separated from each other; penis valve moderately long (0.80 mm); gonostylus 0.81 mm long with terminal expanded part setose on the medial and lateral surface, increasing in density progressively towards the apex ( Fig. 9 e ).

Female bees are characterized by being of moderate size (4.15 mm); mesoscutum bordered with white, short, plumose scale-like hairs; distinct semi-circular dark brown band on the metasomal first tergum and malar space of moderate length (0.12 mm).

Description

Males

Coloration. Head, mesosoma, metasoma black ( Fig. 7 a ). Labrum dark reddish-brown; clypeus black; antennae dark reddish-brown except for basal bulb reddish-brown; compound eyes reddish-brown to dark reddish-brown; ocelli shiny, transparent yellowish-brown ( Fig. 7 a-c). Mesoscutum with three very narrow, shiny longitudinal stripes arising from the anteromedial margin, extending up to the middle of mesoscutum ( Fig. 7 b ). Tegula, pterostigma, veins dark reddish-brown; wings with brownish tinge; metasomal terga black with intersegmental areas light making the metasoma banded ( Fig. 7 a ); terminal terga dark brown; sterna yellowish-brown with dark brown markings.

Pilosity. Labrum fringed with brownish hairs; clypeus, entire face clothed with white plumose long hairs; vertex with long yellowish erect hairs; gena, post-genal margins fringed with long yellowish and greyish hairs ( Fig. 7 a-c). Mesoscutum not bordered by scale-like hairs; mesoscutellum fringed with long yellowish hairs ( Fig. 7 b ); pronotal lobe, mesepisternum and metepisternum with yellowish long plumose hairs with higher density towards the lower margin; anterolateral sides of propodeum with white plumose hairs ( Fig. 7 a ); anterior, posterior and upper surface of hind tibia fringed with white hairs; metasomal terga with short, fine white hairs, the density increasing progressively towards terminal terga; sterna clothed with white hairs with more density towards the medial side and terminal sterna.

Morphometry. Males measure a mean of 6.00 mm in length and 1.82 mm in head width ( Table 1 ); one male as large as 6.40 mm in length and 1.88 mm in head width; head 1.26 mm long; eye 2.37× longer than its width (0.52 mm); upper interocular distance 1.07 mm; diameter of median ocellus 18× greater than malar space length (0.01 mm); interocellar distance 1.67× greater than cello-ocular distance (0.21 mm); scape 0.54 mm long, 0.14 mm wide; forewing 4.78 mm long, 1.69 mm wide; wing diagonal length 1.36 mm; hind tibia 2.20× longer than hind basitarsus (0.70 mm); hind tibial width 1.50× greater than hind basitarsus width (0.38 mm)

The ratio of head length to width 0.69; eye length to upper interocular distance 1.15; interocellar to ocellocular distance 1.67; forewing length to width 2.83; hind tibial length to forewing diagonal length 1.13; hind basitarsus width to hind tibial width 0.67 ( Table 3 ).

Metasomal sterna and genitalia. The following description is based on the dissection of five males. Sternum 4 well sclerotized; gradulus touches the antecosta medially for a short distance; apical margin with a weak emargination, gently sinuate on both lateral sides ( Fig. 9 a ). Gradulus of sternum 5 touches the antecosta; sub-median lobes long, pointed terminating in 2 to 4 spine-like structures; each lobe 0.33 mm long, separated by 0.18 mm from each other with a deep inverted U-shaped concavity; apico-lateral lobes 0.14 mm long, 0.07 mm wide, narrowly pointed, separated from submedian lobe with a shallow broad inverted U-shaped concavity ( Fig. 9 b ) ( Table 2 ). In sternum 6, the antecosta nearly straight with a triangular apicomedial lobe of 0.32 mm length and bluntly rounded apex ( Fig. 9 c ) ( Table 2 ).

Genitalia asymmetrical, dark reddish-brown with well sclerotized gonocoxae and penis valves ( Fig. 9 d ). Left gonocoxa larger (0.23 mm long, 0.44 mm wide) than the right gonocoxa (0.24 mm long, 0.41 mm wide); penis valves asymmetrical; each penis valve 0.80 mm long, 0.33 mm wide at the base; terminal half of each penis valve sharply curved at right angles laterally (curvature in both penis valves highly asymmetrical) terminating into very slender pointed apex ( Fig. 9 d ). Gonostylus tubular, sclerotized and basal 1/3 rd dark brown, remaining 2/3 rd light brown; arise from the lateral basal part of gonocoxa, sinuate at about the mid-length; 0.81 mm long with a width of 0.03 mm at the base, 0.05 mm in the middle and 0.07 mm at the terminal part; series of short and long setae arising from the terminal expanded part on the medial and lateral surface with higher density towards the apex ( Fig. 9 e )

Females

Coloration. Head, mesosoma black ( Fig. 8 a ); labrum, clypeus black; scape black except the basal region and bulb reddish-brown; flagellomeres dark brown; compound eyes reddish-brown; ocelli shiny, transparent, pale ( Fig. 8 c ). Mesoscutum bordered by white scale-like plumose hairs ( Fig. 8 b ). Three very narrow, shiny longitudinal stripes arise from the anteromedial margin, extend up to the middle of the mesoscutum. Tegula, pterostigma, veins blackish brown. All the legs dark reddish-brown except the tarsi light brown. Metasomal first tergum light with the distinct dark brown semi-circular band; remaining terga light brown with a basal margin with a narrow dark brown transverse band thus metasoma appearing banded ( Fig. 8 a, b ); sterna pale.

Pilosity. Labrum with short intermixed with long white hairs; clypeus, entire face, gena and post-gena clothed with dense white plumose hairs; vertex with short erect brown hairs ( Fig. 8 c ). Pronotal lobe, mesepisternum, metepisternum, anterolateral region of propodeum with thick white plumose hairs; lower part with long white hairs ( Fig. 8 a ); mesoscutellum fringed with pale yellow hairs ( Fig. 8 b ). Anterior and posterior margins of hind tibia fringed with brown mixed with white hairs; upper surface with sparse white hairs. Metasomal terga with white fine hairs, the density increasing towards terminal terga. Sterna with long white hairs with high density on medial regions.

Morphometry. Females measure a mean of 4.15 mm in body length, 1.27 mm head length and 1.78 mm in head width; eye 1.09 mm long, 0.42 mm wide; upper inter-ocular distance 3.41× greater than interocellar distance (0.34 mm); median ocellus diameter 1.33× greater than malar space length (0.12 mm); scape 0.65 mm long 0.12 mm wide; mandible 2.36× longer than its width (0.28 mm); forewing 4.32 mm long, 1.47 mm wide; wing diagonal length 1.24 mm; hind tibial length 2.16× greater than hind basitarsus length (0.67 mm) ( Table 1 ).

The ratio of head length to width 0.69 ( Table 3 ); interocellar to ocellocular distance 1.17; scape length to eye length 0.59; forewing length to width 3.04; hind tibial length to head width 0.82; hind tibial length to wing diagonal length 1.19; hind basitarsus to hind tibial width 0.69.

Nest. A colony of this species was in the tree trunk. The entrance tube was 2.5 cm long with a funnel-like opening of 1.5 cm diameter. The entrance tube protruded from the tree trunk, light brown and soft. The brood cells were brown, arranged in multi-layered combs ( Fig. 6 c, d ).

Materials examined. Holotype: Male: Mizoram: Thenzawl (23.2808° N, 92.7741° E, Altitude 783 m a.s.l.), 02.ix.2020, leg. Rojeet T. deposited at UASB . Paratypes: 12 males, 25 females with the same collection data deposited at UASB ; one female paratype will be deposited at ZSIK .

Etymology. The species name is derived from the Sanskrit word “Rajitha” meaning “impressive” referring to large male bees.

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 6. Nest entrance and brood chamber of Lepidotrigona thenzawlensis(a, b), L. rajithae (c, d) and nest entrance of L. amruthae (e)

FIGURE 7. Lepidotrigona rajithae n. sp. Male holotype: a. lateral habitus, b. head, mesosoma and basal part of metasoma dorsal view, c. head frontal view

FIGURE 8. Lepidotrigona rajithae n. sp. Female paratype: a. lateral habitus, b. head, mesosoma and basal part of metasoma dorsal view, c. head frontal view

FIGURE 9. Lepidotrigona rajithae. Male paratype: a. Metasomal sternum 4, b. sternum 5, c. sternum 6, d. genitalia, e. gonostylus terminal part