Myrmica nefaria

Myrmica nefaria is a social parasite of Myrmica rupestris from the Indian Himalaya. Worker, gynes and males have been collected. The species well differs from all already described socially parasitic species of Myrmica and is the second socially parasitic species recorded from Himalaya. This new species seems to follow Emery’s rule, as it somewhat resembles morphologically its host and may have evolved from it. (Bharti 2012)

Identification
By the shape of petiole and post-petiole that are very wide and with big ventral processes, Myrmica nefaria clearly distinguishes from the rest of socially parasitic species that have antennal scape only smoothly curved at the base, with no lobe or carina. These parasitic species have much narrower petiole and post-petiole in gyne (PPI4 < 0.70 vs. > 0.90 in M. nefaria). Similar bizarre shape of petiole and post-petiole has been observed only in one socially parasitic species described to the present date, Myrmica ereptrix, which also has been reported from Himalaya (PPI4 of queen 0.92). Gynes of Myrmica nefaria are somewhat similar to M. ereptrix, but can be easily distinguished from the latter by a number of characters. In Myrmica nefaria the head is very densely ruguloso-reticulate and whole scutum is finely longitudinally rugose, while in Myrmica ereptrix the head dorsum is with divergent longitudinal sculpture and reticulate sculpture presents only on the sides and behind the posterior ocellus, and on scutum sculpture is completely absent in the antero-median V-shaped patch, which is entirely shiny. Posterior part of scutellum and propodeal dorsum is with divergent sculpture, which diverges from centre and curves upward in Myrmica nefaria, but in Myrmica ereptrix these regions are transversely rugose. Similarly, petiole and post-petiole are strongly sculptured with transverse rugosity in Myrmica nefaria, but very weak sculpture is present on both these segments in M. ereptrix. Another conspicuous feature being middle tibia with a well-developed pectinate spur in Myrmica nefaria, while middle tibia lacks spur in M. ereptrix. Propodeal spines are much longer in M. ereptrix than in M. nefaria: ESLI 0.36 in M. ereptrix vs. mean ESLI 0.21 in M. nefaria. Other morphometric differences are: PPI1 0.36 in M. ereptrix vs. 0.55 in M. nefaria (range 0.49 to 0.58); CI 1.32 in M. ereptrix vs. 1.12 in M. nefaria (range 1.11 to 1.15); SI1 0.72 in M. ereptrix vs. 0.77 in M. nefaria (range 0.75 to 0.81); SI2 0.81 in M. ereptrix vs. 0.86 in M. nefaria (range 0.83 to 0.90). (Bharti 2012)

Distribution based on Regional Taxon Lists
Oriental Region: India.

Biology
Bharti (2012) - The nest of host species Myrmica rupestris with M. nefaria was found under a stone, in open grassland with bushes, shrubs, broadleaf trees and widely scattered coniferous trees, recorded air temperature 30°C and relative humidity 68% at the site. Topographically, this valley has two very distinct areas, which differ quite significantly in their environmental conditions. The area which is directly exposed to sun is rock-strewn, dry, with only patches of grass (without herbs or shrubs) harbor maximum abundance of Formica species. The other area is comparatively wet, shady, with ample vegetation has more Myrmica species together with some patches occupied by Temnothorax and Lasius species, and Formica species. The region of Solang valley represents temperate zone of Himalaya and remains snow covered from December to March. Additionally, the region typifies the transitional zone between Greater Himalaya and Trans Himalaya and harbors a rich diversity of flora of both the ecological conditions and is rich in endemic plants. Unfortunately, the area has lot of anthropogenic activities, is listed as fragile ecosystem, and is in dire need of conservation of bio-resources (Kumar et al. 2011).

Evolution
Bharti (2012) - Myrmica nefaria is quite unique in its characters compared to already described socially parasitic species from Palaearctic. Altogether different sculpture of head, alitrunk, petiole and post-petiole, presence of well developed pectinate spurs on mid and hind tibia are some of the significant distinctive features, apart being distinct morphometrically. Its evolutionary tendencies seem novel. The host, Myrmica rupestris, belongs to the primitive M. rugosa species group, while this parasitic species can be placed to the more advanced, younger M. smythiesii group (Radchenko and Elmes 2001, 2010). Generally the species groups have been set up to be phylogenetically meaningful (Radchenko and Elmes 2010), but this may not necessarily apply in all instances (Elmes, G.W., personal comm., September 2011), more exploration of Himalayan Myrmica fauna and further analyses, ideally including molecular genetic analyses, will be needed to definitely clarify the situation. Based on various characters and length of scape in male, M. rugosa group is considered to be primitive in Himalaya, while the M. smythiesii group is considered to be more advanced and younger (Radchenko and Elmes 2001). In M. nefaria the scape length of the male (SI1) and the shape of the frontal carinae of the female castes merging with rugae surrounding the antennal sockets clearly fits to its inclusion in the M. smythiesii group. Thus it is understandable that the parasite is reasonably younger than its host in origin. This fact is supplemented by wing venation as well. The venation pattern in M. nefaria (Figs. 13 and 14) males is different from other socially parasitic males reported so far in having an open (1+2r)+rm cell, where as it is closed in others. A free floating proximal abscissa of Rs is present in M. nefaria males (mostly absent in other species). Furthermore, vein m-cu is complete, m-cu cell is open and veins Rs+m and m are reduced. In the case of females (Figs. 4, 5 and 6), vein Rs instead of bending downwards towards the vein m (as in normal species and social parasites as well), shows an upward tilt in the right wing. The Himalayan Myrmica fauna is exceptional with most of it being endemic, becoming diversified from its ancestral forms concentrated in Himalaya and remaining isolated for a good 25 million years (Bharti 2008a, b; Radchenko and Elmes 2001, 2010); it is quite logical that the younger parasitic species might have diversified in a sympatric fashion from its host. Moreover, this species represents one of the rare cases where inquilines are not completely workerless, but still have the potential to produce its own workers.

Nomenclature

 *  nefaria. Myrmica nefaria Bharti, 2012: 150, figs. 1-17 (w.q.m.) INDIA.

Worker
Head: Head much longer than broad, sides not strongly, but distinctly convex; occipital margin straight; mandibles with six teeth (apical and preapical ones largest, basal tooth broader than 3rd,4th and 5th teeth), mandibles finely longitudinally rugulose and with punctures; clypeus convex, longitudinally rugulose, anterior clypeal margin prominent and rounded medially, sculpture absent on its posterior region, space between rugae minutely punctated and shiny; frontal triangle somewhat deep, weakly shagreenate but shiny; frontal carinae, short almost straight, curving outwards to merge with rugae that surround antennal sockets; antennae 12-segmented, all segments densely punctated except for scape and first funicular segment, which are minutely punctate; scape slender, narrow, weakly curved at base, without any trace of angle or carina, widening towards apex, just extending beyond the upper margin of head, antennae with oblique short hairs and with pubescence on apical 5 segments; eyes large, placed almost at midlength of head; head sculpture finer, more reticulate than in gynes; anterior clypeal margin fringed with setae; head with abundant long suberect hairs, few of long and short, hairs minutely barbulate apically.

Alitrunk, petiole and postpetiole: Alitrunk dorsum feebly convex, promesonotal suture shallow but distinct, metanotal groove broad, deep; pronotum with transverse rugosity and reticulation, rounded anteriorly; mesonotum irregularly rugulose, slightly depressed medially; propodeal dorsum rectangular, with reduced transverse sculpture; declivity smooth and highly polished; propodeal lobes rounded apically; sides of alitrunk longitudinally rugose, with sides of pronotum rugulose, propodeal spines rather short, sharp, projected upward and divergent; tibiae of hind and middle leg with well-developed pectinate spur; the shape of petiole and post-petiole like in gynes; petiole high and narrow, with short anterior peduncle, broader than long, transverse dorsally, post-petiole short, evenly convex, both with transverse rugosity dorsally, anterior face of petiole smooth and of post-petiole shagreenate and shiny, ventral processes of petiole and postpetiole shiny; whole body very hairy, with long standing hairs, few of them minutely barbulate apically, petiole with long subdecumbent hairs directed backwardly, but posterior face of post-petiole has no such hairs.

Gaster and colour like in gynes.

Queen
Head: Head much longer than broad, little broader posteriorly than anteriorly, occipital margin straight, sides convex; mandibles with 7 teeth (apical tooth largest, preapical larger than 3rd one, remaining teeth small), mandibles finely longitudinally rugulose and with punctures; surface of head densely and quite coarsely rugoso-reticulate, with very fine diverging sculpture, which diverges from frontal triangle and at the level of anterior margin of eyes the sculpture ruptures into reticulations with shallow punctures between them, the reticulations become wider, irregular on rest of the head; clypeus convex, shiny, longitudinally rugulose, rugulae absent on the posterior region, spaces between them minutely punctured but shiny, median portion of clypeus raised; anterior clypeal margin slightly prominent medially, without notch; frontal triangle deep, smooth and shiny; longitudinal groove from tip of triangle to the anterior ocellus with a deep pit in the midlength; frontal carinae short, curving outwards, merge with rugae that surround antennal sockets; antennae 12-segmented, densely punctated except for scape and first funicular segment, which is minutely punctated; scape slender, narrow, weakly curved at base without any trace of angle or carina, widening towards apex, just extending beyond the posterior margin of head, antennae with oblique short hairs and with pubescence on apical 5 segments; eyes large, situated almost at the midlength of head; dorsal surface of head covered by long, barbulate hairs, interspersed with short subdecumbent hairs, similar pattern observed on ventral surface of head; thick and long setae present on the anterior clypeal margin; both outer and inner surfaces of mandibles with dense pilosity, some of hairs them are also barbulate.

Alitrunk, petiole and post-petiole: Pronotum transversally rugulose, its sides densely longitudinally rugulose, with a few faint cross-meshes; scutum anteriorly convex, posteriorily depressed, finely longitudinally striate including V- shaped patch; scutellum dorsally irregularly rugulose, posteriorly transversally rugulose; propodeal dorsum with divergent rugosity, declivity smooth and highly polished; propodeal spines thick, elongate-triangular, not pointed, narrowly rounded at tip, diverging outward when seen from above; sides of alitrunk coarsely rugose including anepisternum; metapleural glands moderately large, with a conspicuous orifice dorsally on the bulla; tibiae of hind and middle leg with well-developed pectinate spur; petiole and post-petiole much wider than long, transversally striate dorsally, petiole very shallowly concave dorsally, post-petiole short, evenly convex dorsally, in profile petiole high and narrow, with short anterior peduncle and large keel-like sub-petiolar process, anterior face of petiole smooth, opaque, and that of post-petiole opaque and shagreenate; alitrunk, petiole and post-petiole furnished with numerous short and long suberect to subdecumbent hairs directed posteriorly, thick tuft of such hairs on post-petiole, few of the hairs barbulate apically.

Gaster: Smooth, highly polished and shiny; tergites and sternites with short, suberect pubescence between the longer suberect hairs, few barbulate hairs on last tergite of gaster like those on head and alitrunk, petiole and post-petiole. Head, alitrunk, petiole and post-petiole dark brown, scape, mandibles (except masticatory margin, which is black) and legs reddish yellow.

Right and left forewing venation (Figs. 4, 5 and 6): The cells (1+2r) + rm and m-cu are closed, the free floating proximal abscissa of Rs shows an upward tilt in right wing.

Male
Head: Suboval, slightly longer than broad, little broader posteriorly, with convex sides; mandibles with apical and preapical teeth only, punctated and very weakly striated clypeus finely irregularly rugulose; frontal triangle deep, shagreenate but shiny; broad longitudinal groove from tip of triangle to anterior ocellus; frontal lobes reduced and condylar bulb completely visible; antennae 12 segmented, densely punctated like in gynes and worker; scape long and slender, almost equal to 7 following funicular segments, extending beyond the upper margin of head, slightly curved from base to 3/4th of length, widening towards apex, with a moderately defined 4-segmented antennal club, antennae with oblique short hairs and with pubescence only on apical 4 segments; eyes large, placed somewhat below the midlength of head; head sculpture fine, hair pattern similar to gynes but hairs not barbulate and subdecumbent.

Alitrunk: Pronotum like in gynes but with weak sculpture; scutum convex, punctated, not longitudinally rugose, somewhat smooth, shiny, but V-shaped patch longitudinally striated; scutellum weakly irregularly striate, punctated and transversally striate posteriorily; propodeum dorsum divergently rugulose, with its middle portion smooth and shiny, declivity smooth, highly polished; propodeum with blunt tubercles; metapleural lobes rounded; tibiae of hind and middle leg with well-developed pectinate spur; sculpture of sides of alitrunk less dense than in gynes; petiole and post-petiole much broader than long, petiole dorsally convex, postpetiole evenly rounded (unlike gynes where petiole is very shallowly concave dorsally and postpetiole only convex dorsally); petiole finely transversally striate, punctated, while post-petiole smooth and shiny; hair pattern similar to gynes except for absence of subdecumbent and barbulate hairs.

Gaster: Smooth, highly polished, hair pattern similar to gynes except for absence of subdecumbent and barbulate hairs.

Fore wing venation (Figs. 13 and 14): A free floating proximal abscissa of Rs is present, veins Rs+m and m are reduced. Thus cells (1+2r)+rm and m-cu are open, vein m-cu is complete.

Type Material
Holotype Gyne (alate): India, Himachal Pradesh, Solang Valley (32.312°N, 77.1556°E), 2469 meters a .s. l., 20 .VI. 2010, leg. H. Bharti. Paratypes, 62 alate gynes, 5 workers and 4 alate males from the nest of holotype (collected together with 42 host workers from the same nest). Holotype and paratypes together with host series are in (DST code-1594) and some of the paratypes will be deposited in.

Etymology
From the Latin word nefaria that means “criminal”.