Myrmica radchenkoi

Bharti and Sharma (2011) - Myrmica radchenkoi is known from the Indian Himalaya. The type material was collected from leaf litter in a patchy Cedrus forest and the area is a transitional zone between temperate and sub temperate Himalaya. The ambient temperature at the collection site was 32°C and the nest temperature was 30°C (Bharti & Sharma, 2011b; Bharti et al., 2016).

Identification
Bharti and Sharma (2011) - Due to long propodeal spines (ESLI 0.42) and very long peduncle of petiole (PI1 1.86) and altogether different sculpture of head and alitrunk, Myrmica radchenkoi can be clearly separated from its close ally Myrmica rigatoi (where PI1 1.65 and ESLI 0.52). On the basis of clypeus without median notch, propodeal spines very long, propodeal lobes rounded, M. rigatoi has been provisionally placed in the inezae group (Radchenko & Elmes 2010). This group is currently represented by three species only (Myrmica inezae, Myrmica mixta and Myrmica rigatoi) distributed in Himalaya and South-western China. This group shares several features with the ritae group, but due to absence of median notch at anterior margin of clypeus, it was separated as a distinct group. It is believed that this group represents an old relict fauna of Myrmica derived froma ritae-like ancestor which was isolated in Central Asia where it adapted to high altitude regions and underwent speciation (Radchenko & Elmes 2010). Earlier Myrmica rigatoi was placed in the ritae group (Radchenko & Elmes 2001) but was shifted provisionally to the inezae group (due to lack of sufficient representative species of its kind). With the discovery of Myrmica radchenkoi this placement seems quite justifiable as the queen of Myrmica radchenkoi that has been described here shares some important features with already reported queen of Myrmica inezae (Radchenko & Elmes 2002). Both have long propodeal spines, rounded propodeal lobes, tranverse rugosity on sclerite bordering scutellum and anterior margin of propodeum (in Myrmica radchenkoi PI1:1.97, ESLI: 0.36, ESDI: 1.17 and in Myrmica inezae PI1:1.63, ESLI:0.41, ESDI: 0.76). Therefore it is advocated that the placement of Myrmica rigatoi and of course Myrmica radchenkoi in the inezae group is correct and may be further substantiated in the near future with discovery of males in this group.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Nomenclature

 *  radchenkoi. Myrmica radchenkoi Bharti & Sharma, 2011b: 430, figs. 1-6 (w.q.) INDIA.

Worker
FLW:0.40, FW:0.38, HL:1.13, HW:0.88, SL:1.01, PL:0.58, PPL: 0.42, PW: 0.25, PPW: 0.37, PH: 0.32, PPH: 0.39, AL: 1.61, TL: 5.09.

Head: Head in dorsal view much longer than broad, occipital margins slightly convex; mandibles with 7 teeth, longitudinally striate, apical tooth large; palp formula 6:4; dorsal surface of head with reticulate sculpture which is quite irregular and wide, surface between reticulations shining, very weakly punctated; clypeus shining with prominent longitudinal striations in the middle; frontal triangle shining; frontal carinae running straight and in some specimens slightly curved outward to merge with rugae that surround the antennal sockets; roughly 16-17 rugae between the frontal carinae at the level with eyes; antennae 12 jointed, scape slender curved at the base, punctured, opaque, finely longitudinally striate, without any trace of lobe or carina, extending ¼ beyond the upper margin of head, funicular club with apical 4 joints; eyes large, placed below midline of head; dorsal surface of head covered with interspersed erect hairs; anterior margin of mandibles densely pilose, along with sides of head, scape, similar oblique hairs present on flagellum and along with pubescence.

Alitrunk, petiole and postpetiole: Pronotum rounded anteriorily; alitrunk dorsum feebly convex, pro-mesonotal suture shallow but distinct; metanotal groove broad and shallow; longitudinally striate; pronotum transversally striated anteriorly with wide longitudinal striations posteriorly; mesonotum, roughly transversally striated; propodeum with few coarse transverse rugae (behind the metanotal groove a single transverse carina present), declivity smooth and shining; propodeal lobes rounded; propodeal spines very long, pointed and directed upwards; sides of alitrunk longitudinally striated with striations wide apart; mid and hind tibae with pectinate spurs; petiole with a very long peduncle (PLI 1.80), petiole with sharp subpetiolar process, petiole much longer than broad (PL 0.56, PW .035); petiolar node with fine transverse striations; postpetiole longer than broad, smooth dorsally, longitudinal in profile; whole of the alitrunk covered with very long erect hairs along with petiole and postpetiole; legs with similar type of pilosity but hairs shorter in length.

Gaster smooth, covered with long erect pilosity which is dense on last gastral tergite and sternite.

Color dark brown, with legs, mandibles and antennae light brown.

Queen
FLW: 0.45, FW: 0.41, HL: 1.21, PL: 0.75, PH: 0.38, ESL:0.35, HW: 0.97, SL: 1.02, PPH: 0.45, PPW: 0.49, PW: 0.33, PPL: 0.43, ESD:0.41, SCW:0.89, SCL: 1.36, AL: 1.94, AH: 1.13, TL: 6.33 CI:1.25, FI :0.45, FLI:1.09, PI1:1.97, PI2:0.77, PI3:0.34, PPI1:0.95, PPI2:0.91, PPI3:1.48, PPI4:0.41, SI1:0.84, SI2:1.05, ESLI:0.36, ESDI: 1.17.

Head: Similar to worker except mandibles with 8 teeth, apical tooth very large, longitudinal striations on the mandibles and clypeus more dense and fine.

Alitrunk, petiole and postpetiole: Pronotum transversally striate in frontal view, with cross meshes or reticulate sculpture on anterolateral corners and rest of it in profile finely longitudinally striate; scutum and scutellum as a whole very finely longitudinally striate, sclerite between scutellum and propodeum transversally striate; petiole with long peduncle (PLI 1.97); postpetiole broader than long, rest like worker.

Type Material
Holotype Worker: India, Jammu and Kashmir, Machedi, 32.72364°N,75.669464°E, 2000 meters above msl, 3rd August, 2008. Paratypes, 3 workers and 1 queen with same data as that of holotype. Holotype and paratypes in Department of Zoology {Dr Himender Bharti’s Collections-DST (YEG)-550, DST (YEG)-557 to DST (YEG)-560}, Punjabi University Patiala, India.

Etymology
The species is named after Professor Alex Radchenko for his contribution to genus Myrmica.