Leptanilla hypodracos

Leptanilla hypodracos was collected from a well-shaded patch of tropical low-lying old secondary forest with a high density of leaf litter and woody debris onthe forest floor. As with other Leptanillinae, L. hypodracos presents a hypogaeic lifestyle and was collected in a baited subterranean pitfall trap at a depth between 10–15 cm. Colony size and structure is unknown. Although the specimens were collected in a trap containing tuna bait, it is presently unclear as to whether L. hypodracos were recruited to the bait, since other Leptanilla species have previously been suggested to be specialist predators of geophilomorph centipedes (Masuko 1990) and have yet to demonstrate any scavenging habits.

Identification
Based on a morphological examination, L. hypodracos is close to several other Leptanilla from the Oriental region, namely Leptanilla escheri Kutter, 1948, Leptanilla butteli Forel, 1913, and Leptanilla thai, but is most similar to Leptanilla clypeata. Leptanilla hypodracos differs from L. escheri in the anterior margin of the petiole in profile view, which is rounded in L. hypodracos but more angular in L. escheri while in dorsal view, L. hypodracos displays a long and narrow petiole (PI = 47, PPI = 83) that contrasts with the rounded petiole which is as wide as it is long in L. escheri (PI = 87–120, PPI = 117–145). In dorsal view L. hypodracos also has a narrower mesosoma than L. escheri. Furthermore, as records of L. escheri are restricted to southern Indian highlands where the elevation ranges from 1250 to 1775m asl, and L. hypodracos was collected in a tropical lowland forest of Singapore at an elevation of 55m asl, it is conceivable that the two species occupy differing ecological niches. Similar species reported from the Malay Peninsula include L. butteli from West Malaysia and L. thai from Southern Thailand. However, L. hypodracos is distinguished from these species in having a more rounded petiolar node and a less inflated petiole.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Singapore.

Castes
Known only from the worker caste.

Nomenclature

 *  hypodracos. Leptanilla hypodracos Wong & Guenard, 2016: 132, figs. 1-7 (w.) SINGAPORE.

Worker
Head. Head longer than wide (CI = 76–78). In full-face view, posterior margin of head straight to slightly concave. Lateral margins of head slightly convex with posterior margins rounded. Eyes absent. Anterior clypeal margin extending forward with two rounded lobes anterolaterally and slightly concave on its anteromedian portion (Fig. 1B). Median portion of clypeus raised. Mandibles short relative to head(MaI = 54–57) armed with three teeth. Mandibles with a distinct ridge on their basal margin (Fig. 2B). Apical tooth large and acute followed by two smaller teeth; with the basal tooth significantly smaller, blunt and pointing inward. Antennal insertion exposed. Antennae with 12 segments. Scape inflated in its median portion, dorsally concave, andextending over the mid-point of head. Pedicel distinct from the scape and flagellum by marked constrictions. Flagellum incrassate with the last antennal segment distinctly longer than the previous flagellomeres, about the size of the previous two segments.

Mesosoma. In lateral view, mesosoma with a continuous straight appearance with the exception of a well-marked interruption of the promesonotal suture (Fig. 3B). In dorsal view, pronotum wider than posterior portions of mesosoma, especially on its anterior half (Fig. 4B). In profile view, a distinct sulcus of fine striae separates the pronotum from the propleuron extending from the dorsal portion of the neck and reaching the inferior part of the promesonotal suture just above the coxal junction (Fig. 5B). In profile view, both anterodorsal and anteroventral parts of pronotum rounded with the latter droplet-shaped. Mesonotum and propodeum with similar width and without obvious inflated portion. Promesonotal suture deeply impressed and clearly visible in both dorsal and profile view. Metapleural gland bulla large and elongate, nearly as large as the maximum width of hind coxa (Fig. 6B). Posterior part of propodeum forming the propodeal declivity nearly at right angle with rounded edges.

Metasoma. In profile view, dorsal and ventral portion of petiolar node markedly convex, rounded without acute portion nor subpetiolar process. Dorsal margin of postpetiole convex and rounded. Dorsal margin of the postpetiolar node lower than the maximal height of the dorsal margin of the petiolar node. Sternopostpetiolar process welldeveloped and rounded. In dorsal view, petiolar node longer than wide (PTL = 0.10 mm, PTW = 0.06 mm) while postpetiole more rounded (PPL = 0.09 mm, PPW = 0.08 mm).

Sculpture. Sculpture absent on most of the body. Most of the body with a slick and shiny appearance with the exception of the neck with clear transversal striae (Fig. 7B). Hair insertion on head giving an impression of the presence of small punctuations.

Pubescence. Pubescence present on most of the body, especially on dorsal parts. Antennae and mandibles with numerous erect to suberect long hairs.

Coloration. Head, thorax and fore coxa with a dark amber colour, while petiole, postpetiole and most of the gaster slightly lighter. Antennae, legs (with the exception of the fore coxa) and tip of the gaster with a much lighter yellow coloration.

The species epithet is derived from a combination of the Latin terms for ‘under’ and ‘dragon’, in reference to the slender, dragon-like appearance of this subterranean predator. The species epithet is a noun, and thus invariant.
 * Eytomology.