Rhysida ikhalama, Joshi & Karanth & Edgecombe, 2020

RHYSIDA IKHALAMA SP. NOV.

( FIG. 15)

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Diagnosis: Twenty antennal articles. Prominent median ridges from T3. Paramedian sutures complete from T3. Coxopleural process with two apical spines, lacking subapical, dorsal and lateral spines. Ultimate leg prefemur with VL2 spines only.

Type material

Holotype: CES101438 , Miao , Chanlang district, Arunachal Pradesh, India (27.48°N, 96.20°E, 250 m a.s.l.), collected by Jahnavi Joshi, 13 April 2011. GoogleMaps

Paratypes: CES101440 , Miao , Chanlang district, Arunachal Pradesh ; CES101438 , Miao , Chanlang district, Arunachal Pradesh, India . Locality coordinates in the Supporting Information ( Table S1).

Etymology: From the Lisu word for centipedes. Lisu is one of the tribes residing in Miao, Arunachal Pradesh. It is a noun in apposition.

Description: Length ≤ 30 mm. Twenty antennal articles, basal three articles glabrous dorsally and three ventrally ( Fig. 15A). Cephalic plate smooth. Longitudinal median furrow on anterior 10% of the cephalic plate. Cephalic plate and T1 reddish, the following tergites red and pale brown; legs pale yellow. Forcipular coxosternal tooth-plates with 5 + 5 teeth in a group of three inner and two outer, the outermost smaller than inner three large teeth; innermost tooth small; base of tooth-plates defined by oblique sutures diverging at 160° ( Fig. 15B, D). Trochanteroprefemoral process bearing two apical teeth and one lateral tooth. Tergites with paramedian sutures complete from T3. Tergites not marginated but with distinct median ridge starting from T3. Tergites with a shallow depression on both sides of paramedian suture ( Fig. 15H). Paramedian sutures 10% length of sternites ( Fig. 15G). Tergite of ultimate leg-bearing segment wider than long, with parallel lateral margins, posterior margin convex but with a nearly transverse median extent ( Fig. 15E). Sternite of ultimate leg-bearing segment slightly longer than wide, lateral margins strongly converging posteriorly, posterior margin concave, with an angle of 110°; weak longitudinal median furrow ( Fig. 15C). Coxopleural process moderately long; coxopleuron ~1.5 times the length of sternite of ultimate leg-bearing segment; coxopleural process with two apical spines, lacking subapical and dorsal or lateral spines. Pores dense, with pore-field terminating distinctly beneath dorsal margin of coxopleuron; non-porose area on coxopleural process narrow, short ( Fig. 15C). Ultimate legs relatively short, with prefemur ≤ 3.5 mm, femur ≤ 3 mm, tibia ≤ 2.25 mm, tarsus 1 ≤ 1.5 mm and tarsus 2 ≤ 0.75 mm. Prefemur with VL2 ( Fig. 15I, J). Legs 1–18 with two tarsal spurs, legs 19–20 with one tarsal spur. Leg 1 with a tibial and femoral spur.

Distribution: This species is recorded from eastern Arunachal Pradesh (also known as Eastern Himalaya) in northeast India, part of the Himalayas biodiversity hotspot. The forests are contiguous with Myanmar and are biogeographically recognized as a distinct subregion, Indo-Burma ( Myers et al., 2000).

Remarks: Phylogenetically, this species is distinct and the sister species to other members of the R. immarginata clade ( Fig. 3). A total of three individuals from the same locality are sampled and, for two individuals, COI successfully sequenced, depicting no variation between those two individuals. Both GMYC and mMPT retrieve a single distinct species ( Fig. 3).

The presence of distinct median ridges from T3 distinguishes this species from the rest of the R. immarginata clade. It is additionally distinct in having paramedian sutures complete from T3 (vs. TT 4–6 in other Indian species of the R. immarginata group). Having prefemoral spines confined to the VL row is shared only with R. aspinosa in this clade, but R. ikhalama has VL2 vs. VL 1 in R. aspinosa . These two species are grouped in having the coxopleuron bearing only (two) apical spines.