First description of the sexuals of Camponotus opaciventris Mayr, 1879 (Hymenoptera, Formicidae), with notes on distribution in Western Himalaya

Abstract Background The taxonomy of Camponotus ants in India is mostly based on the worker caste, described in about 96% of the known species (AntWeb 2016). However, nearly 48% of these ant species are only known from workers, with no record of sexual forms. To improve knowledge of Indian Camponotus, we here describe sexuals of Camponotus opaciventris Mayr 1879. New information The hitherto unknown sexuals of Camponotus opaciventris Mayr 1879 are described for the first time. Workers are redescribed and distribution of this ant species in Indian Western Himalaya is herewith detailed.


Introduction
Camponotus Mayr (1861) is the world's largest and widespread genus of ants found in all biogeographical regions (Hölldobler andWilson 1990, AntWeb 2016). It is currently represented by 1,099 species and 495 subspecies, supplemented by 32 fossil species (AntWeb 2016). In India this genus is represented by 83 species and subspecies (AntWeb 2016, , however the status of many species and subspecies remains dubious and unclear (Bharti and Wachkoo 2014, Bharti and Wachkoo 2015. Camponotus opaciventris has a history of taxonomic confusion (Dietrich 2004); it was described in 1879 and later was synonomized with Camponotus sericeus (Fabricius 1798) by Bingham (1903). Subsequently Forel (1892), Forel (1908) treated it as infraspecific taxon of C. sericeus whilst Emery (1896), Emery (1925), Radchenko (1996) followed this view. Most recently, Dietrich (2004) revived C. opaciventris from synonymy raised it back to species status. Camponotus opaciventris is well represented in collections from Indian Western Himalayas, but has been frequently misidentified as widespread C. sericeus (Wachkoo 2013).
Western Himalayan region in India is represented by the states of Jammu and Kashmir in the west, Himachal Pradesh in the middle and Uttarakhand in the east. Faunal diversity of Western Himalaya is rich and diversified due to varied climatic conditions ranging from tropical in Shivalik foothills to very cold environment in the Trans Himalaya. There is a dominance of Palaearctic and endemic fauna above timber line (3000 m) and Oriental and some Palaearctic and Ethiopian elements at lower and middle altitudes (Sidhu et al. 2012, Shah et al. 2014).
On examining our material collected from Western Himalayas and Western Ghats we find no evidence for the presence of C. sericeus in the Western Himalayas. For this reason and hitherto unknown sexuals we redescribe the worker caste and describe the queen and male castes for the first time. Images of all castes and a worker based comparative diagnosis are provided to clarify the species boundaries of C. opaciventris and C. sericeus. Information on the distribution and ecology of this species are also given.

Materials and methods
The specimens were obtained by visual searching and hand-collecting. The morphological study was conducted on a Nikon SMZ 1500 stereo zoom microscope. For digital images, an Evolution MP digital camera was used on the same microscope with Auto-Montage (Syncroscopy, a division of Synoptics Ltd.) software. The images were processed with Adobe Photoshop CS5. Specimens examined for this study are deposited in PUPAC, Punjabi University Patiala Ant Collection and NHMW, Natural History Museum, Vienna, Austria. Some worker specimens will be deposited in BMNH, Natural History Museum, London, U.K. and CASC, California Academy of Sciences, San Francisco, United States of America. Morphological terminology for genitalia follow (Boudinot 2013); measurements, in millimeters, and indices follow (Wachkoo 2015) and are provided below.
HL -Maximum length of head in full-face view, measured in straight line from the anteriormost point of the median clypeal margin to the midpoint of the posterior head margin.
HW -Maximum head width in full-face view, excluding the portion of eyes that extends past the lateral margins of the head.  Head triangular, wider than long in major worker, lateral margins arched, posterior margin transverse to gently convex; scapes short, surpassing posterior margin of head by less than one-fifth their length; head of minor worker subquadrate longer than wide, with gently arched lateral margins and convex posterior margin; scapes of minor worker longer, surpassing posterior margin of head by one-fourth their length; clypeus subcarinate; anterior clypeal margin emarginate in major worker, convex in minor worker not projected beyond anterior margin of gena; anterolateral corners broadly rounded; mandibles subtriangular, robust, armed with 5-teeth.
Body covered sparsely with short appressed pubescence, denser on gaster but not hiding the cuticular sculpture; whole body covered with erect setae; setae on propodeum denser than promesonotum; hindtibia with irregular multiple rows of spiny bristles in addition to 3-4 suberect setae at distal end near spurs. Head and antennae reddish, remainder of body dull black.
Queen Fig. 2a As in major worker, with modifications expected for caste and the following differences: head squarer than in major worker; mesosoma and gaster densely pubescent; mandibles 5-toothed; scutum and scutellum with shallow widely spaced punctures; declivous face right angle.
Male Fig. 2d, e, f Head wider than long including eyes; scapes long, surpassing posterior margin of head by about two-fifths their length; clypeus subcarinate in middle with nearly transverse anterolateral corners; mandibles slender, curved strap like, apical tooth acute, remainder without any teeth or denticles; when closed their tips overlap.
Pygostyles distally setose; basimeres large, broad at the base with bluntly rounded apex; in dorsal view, telomeres elongate anteroposteriorly and curved inward; in lateral view tubular, rounded apically covered by punctures; basimeres with sparse setae, telomeres abundantly setose; cuspides small bent toward digiti; digiti much longer than cuspides, about 2 times the length of cuspides bent towards each other apically; penisvalva projecting with apices of each penisvalva directed posterolaterally.
Vestiture as in major worker with following differences: propodeum shiny without any setae on dorsum; gaster less pubescent than in other conspecific castes.

Ecology
These ants have been observed to form nests in sandy soils, dry soils and under large stones. The minor workers were collected largely individually at foraging while most of the major workers remained inside the nests. Camponotus sericeus (Fabricius, 1798); major worker and queen a: Head, full-face view (major worker); AntWeb: CASENT0104896, courtesy April Nobile b: Body, lateral view (major worker); AntWeb: CASENT0104896, courtesy April Nobile c: Body, dorsal view (major worker); AntWeb: CASENT0104896, courtesy April Nobile d: Head, full-face view (queen) e: Body, lateral view (queen); cuticle obscuring pubescence of gaster abraded in specimen f: Body, dorsal view (queen); cuticle obscuring pubescence of gaster abraded in specimen