Romblonella longinoi

This Malaysian species, currently known from a single nest series, was collected from a dead stem in a wet tropical forest.

Identification
The worker of R. longinoi is distinguishable from the workers of all known species of the genus in its head capsule that is posteriorly broadened. All other species possess a head capsule that is roughly parallel-sided. Other morphological differences are summarized in the key. In addition, R. longinoi workers are colored differently from any other Romblonella species.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Malaysia.

Nomenclature

 *  longinoi. Romblonella longinoi General, 2016: 113, figs. 1-15 (w.m.) MALAYSIA (Sabah).

Description
In full face view, posterior margin of head shallowly emarginate; head longer than wide; sides of head diverging posteriorly; eyes laterally located, slightly behind midlength of head; shallow scrobe present; frontal carina long, almost reaching the posterior margin of head; scapes short, exceeding posterior edge of eye by about 2X width of distal scape; antennal formula 12:3; mandibles triangular, with 6 robust teeth; palp formula 5:3; median clypeus carinate, with a median carina flanked by 3 pairs of lateral carinae; median clypeus inserted between frontal lobes and about as wide as frontal lobe; anterior clypeal margin entire, without an isolated median seta; head rugoreticulate with short cross-hatches that reach the adjacent rugae; punctae in interstitial spaces; mandibles striate. In lateral view, dorsal margin of mesosoma evenly convex and arched, without grooves or sutures; propodeal spines long and stout; petiole sessile, with anterodorsally directed angle over petiolar spiracle; petiole massive, larger and taller than postpetiole; anterior subpetiolar denticle present; spurs absent on meso- and metatibia. In dorsal view, pronotum with angulate humeri; sides of promesonotum converging posteriorly; sides of propodeum subparallel but bulging slightly anterior to propodeal spiracle; stout propodeal spines slightly divergent through their entire length; mesosoma, petiole and postpetiole dorsally reticulate with interstitial punctulae; first gastral segment(= 4th abdominal) punctulate. Head with evenly distributed short, blunt erect hairs that are shorter than distance between them; scape with suberect hairs; short, blunt erect hairs sparsely distributed over rest of body. Body distinctly bi-colored; body yellow to orange except for brown antennal club, legs, distal and lateral edges of first gastral segment, and gastral segments 2-5. Alate; approximately as long as worker, but more gracile. In full-face view, head longer than broad; sides of head diverging posteriorly, posterior head width behind compound eyes about ¾ wider than anterior head width; ocelli not unusually large (compared with images of male R. palauensis, M.R.Smith, 1953), width of ocelli subequal to distance between lateral ocellus and median ocellus; lateral ocelli separated by about 2X width of median ocellus; compound eye large, convex, occupying about 2/3 side of the head; posterior margin of head medially straight, laterally with lobes; antenna long, subfiliform, with 13 segments (Figures 6 and 7); length of antennomeres (one male measured) antennal scape, 0.08 mm; antennomere 2, 0.04 mm; antennomere 3, 0.27 mm; antennomere 4-7, range = 0.12-0.19 mm; antennomere 8, 0.23 mm; antennomere 9-13, range = 0.13-0.18 mm; antennomere 4-7 slightly and gently broadened distally, such that the basal end of succeeding segment is narrower than the distal end; antennomere 3-7 broader than antennomere 8-13; clypeus broadly projecting anteriorly, forming a rounded obtuse angle; mandible triangular, well-developed and functional; masticatory margin with 6 sharp triangular teeth; apical tooth longest, about 2X longer than preapical tooth; tooth 4 smallest; rest of teeth subequal; palp formula 5:3. In lateral view, lower portion of compound eye not obscuring gena and ventral margin of head; pronotum with a flat dorsal outline; mesonotum forming a low dome that slopes gently posteriorly to the propodeal dorsum; mesepimeron not bearing epimeral lobe; vertical impression on anterior third of metakatepisternum; propodeal spiracle circular; propodeal declivity almost vertical, forming a rounded obtuse angle with the propodeal dorsum; petiole tube-like, more than 2X longer than tall, with an indistinct, truncated node; postpetiole about half as long as petiole, with a low, rounded node; first gastral segment (AIV) longest, about half the length of gaster; tibial spurs absent on middle and hind legs; external genitalia as in Figures 11 to 14. In dorsal view, notauli and parapsidal furrows present; notauli abbreviated, not meeting posteriorly; petiole longer than wide; postpetiole wider than petiole; gaster elongateovate. Forewing (Figure 9) with pterostigma; cross-veins 1r-rs and 2r-rs present; free abscissa 2rs-m originating at distal 2/3 of Rs (radial sector) vein. Four closed cells present: C, R, 2R1, and 3R1.
 * Description of worker.
 * Diagnosis of male paratype.

Clypeus carinate, with about 6 short, sinuate longitudinal carinae; head longitudinally rugulose, with short cross-hatches that do not reach the adjacent rugula, and with a ground surface of fine reticulation; mandibles longitudinally carinate; dorsal mesosoma ruguloreticulate; propodeum transversely rugose; petiole dorsally and laterally rugo-reticulate; postpetiole dorsally and laterally ruguloreticulate; gaster finely reticulate dorsally. Pale yellow erect and sub-erect hairs evenly but sparsely distributed all over body; legs with decumbent hairs; antennae with yellowish, short, fine hairs. Body and distal 5 antennal segments brown; mandibles, basal 8 antennal segments and tarsi yellowish-brown.

Gyne unknown. This species is dedicated to my friend and colleague, Dr. John T. Longino, who collected this rare nest series with 2 associated males.
 * Etymology:

References based on Global Ant Biodiversity Informatics

 * General D. E. 2016. Romblonella longinoi (Hymenoptera: Formicidae), a new species and first record of the genus from Sabah, Malaysia, with a key to the species of Romblonella Wheeler, 1935. Halteres 7: 112-119.
 * General D. E. M. 2016. Romblonella longinoi (Hymenoptera: Formicidae), a new species and first record of the genus from Sabah, Malaysia, with a key to the species of Romblonella Wheeler, 1935. Halteres 7: 112-119.