Myrmoteras scabrum

Known from the holotype, collected from a mature evergreen forest, and a second from the Thanikuddy region of the Periyar Tiger Reserve, West Ghats, India (Akbar & Bharti, 2020).

Identification
Moffett (1985) - Head and trunk conspicuously sculptured. M. scabrum can be distinguished from closely related Myrmoteras ceylonicum by its larger size; the stronger granulo-rugose sculpture on the head; very conspicuous mandible bend; evenly convex (rather than flattened) pronotum; node of petiole wider than tall in side view; and much darker color.

Bharti & Akbar (2014) - M. scabrum is a very distinct species belonging to subgenus Myrmoteras. M. scabrum is easily identified with its conspicuously sculptured head and mesosoma. M scabrum can be distinguished from closely related Myrmoteras ceylonicum by its larger size; stronger granulo-rugose sculpture; conspicuous mandible bend; convex pronotum; node of petiole wider than tall and much darker colouration.

Akbar & Bharti (2020) - M. scabrum is a distinct species belonging to subgenus Myrmoteras s.str. The species is easily identiﬁed with its conspicuously sculptured surface of head and mesosoma. M. scabrum can be morphologically distinguished from closely related Myrmoteras ceylonicum Gregg, 1957 by its larger size; stronger granulo-rugose sculpture; conspicuous mandible bend; convex pronotum in lateral view; node of petiole wider than tall and much darker colouration.

Distribution
Akbar & Bharti (2020) - The two known distributional records suggest that the species may be present throughout the Western Ghats belt of India, as the known records are spread well apart from each other. The lack of any substantial reports of the species from the region suggests that the species may be rare and infrequent in occurrence. However, it also cannot be ruled out that the apparent rarity may be due to an inadequate collection method; likely, it has already been veriﬁed for many other ant species, rarity of whom was debugged after the application of new collection techniques.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Biology
Akbar & Bharti (2020) - A single specimen of M. scabrum was collected from the Thanikuddy region of the Periyar Tiger Reserve while it was foraging on the leaves of small Indian sandalwood tree (Santalum album), planted on the rear side of the Inspection Bungalow. The Inspection Bungalow is the only manmade structure present in the entire core area (Thanikuddy region) of the reserve. A deep and wide trench is made around the Inspection Bungalow for the animal protection. It cuts the place from the rest of the intact forest area. The species may be a solitary forager as much time and continual sampling was done during the day and in following days but without any additional specimen collection. Collection of the specimen near the site may be accidental or preference of the species towards anthropogenic pressures or habitat conversed areas.

Nomenclature

 *  scabrum. Myrmoteras (Myrmoteras) scabrum Moffett, 1985b: 30, figs. 21, 24 (w.) INDIA.

Worker
Holotype: TL 5.5, HW 1.25, HL 1.12 (CI 112), ML 1.13 (MI 101), SL 1.31 (SI 105), EL 0.73, HFL 1.38 (TWI 16), WL 1.68 mm. Larger than Myrmoteras ceylonicum and Myrmoteras brachygnathum. Frontal sulcus absent, although a weak medial ridge extends from clypeus to a point just above antennal bases. Frontal area present, better defined than in M. ceylonicum. Scapes relatively longer than in M. ceylonicum holotype, overreaching posterior border of head at about 50% of their length. Clypeus raised medially somewhat more prominently than in most species in the subgenus but not to the degree found in M. ceylonicum and brachygnathum; clypeal teeth exceptionally strong. Maxillary palps four, labial palps apparently two. Mandibles with two to three preapical denticles; shafts strongly bent at tips, so that when seen from above with the proximal portions of the shafts in the plane of view the apical tooth and apical denticles are virtually directly behind the penultimate tooth. Mandibles relatively strongly depressed, 46% wider than deep at position of fifth tooth (about half way to apex); in single specimens selected at random from each of the other species in the subgenus the mandibles varied from 26 to 35% wider than deep at this point.

Trunk as described for M. ceylonicum but propodeum less strongly depressed. Anterior and (except at base) posterior faces of petiolar node virtually straight, with the anterior face steeper, meeting peduncle rather abruptly at an obtuse angle; posterior face curving gently into posterior peduncle. Summit of node flat or slightly concave in profile as in M. ceylonicum, with ridges along anterior and posterior apices somewhat better developed. Node 20% broader than high, versus 45% higher than broad in ceylonicum. Middle and hind tibiae only slightly swollen, parallel sided throughout most of their lengths.

Dorsal surface of head densely granulorugose, coarser (grain ca. 0.02 to 0.03 mm across) and more irregular than in M. ceylonicum; this sculpturing weaker and less dense on clypeus (which is virtually smooth mesad) and on back of head. Smooth laterally beneath eyes except for faint longitudinal rugae; ventrum of head smooth. Pronotum densely and very irregularly rugose, rugae largely transverse; mesothorax with prominent longitudinal rugae ca. 0.04 mm apart dorsad and laterally; similar rugae laterally on propodeum. Propodeum dorsally and behind with narrow transverse rugae as in M. ceylonicum but more closely spaced, ca. 0.02 to 0.03 mm apart. Gaster and legs smooth and shining. Pilosity very dense, with more than 40 hairs breaking dorsal margin of trunk in profile. Hairs long, rising to 0.15 mm on head and 0.20 mm on trunk and gaster. Two hairs on or near each metathoracic tubercle; node of petiole with two rows of five to six well-spaced hairs along anterior and posterior ridges and down onto sides of node. Very dark orange red with legs and gaster relatively lighter and antennae and mandibles yellowish orange; tarsi yellow.

Type Material
Holotype. Worker deposited in MCZ from India: Kerala State: Cannanore Dist.: Peria Reserve (Western Ghats), 4-5.IV. 1969, ca. 900 m, evgrn. for. (A. B. Scans and W. L. Brown).

Etymology
Name derived from Latin scabra, referring to the heavily sculptured head and trunk.

References based on Global Ant Biodiversity Informatics

 * Dad J. M., S. A. Akbar, H. Bharti, and A. A. Wachkoo. 2019. Community structure and ant species diversity across select sites ofWestern Ghats, India. Acta Ecologica Sinica 39: 219–228.