Syllophopsis gongromos

Identification
Heterick (2006) - The small red-and-yellow workers of M. gongromos closely resemble those of some populations of Syllophopsis hildebrandti, but are distinguished by the presence of humeral angles (evident as small protuberances or rugosities in full-face view) and by numerous, fine, transverse striolae on the dorsum and upper sides of the propodeum. The dorsum of the mesosoma in dorsal view is subcarinate transversely between the humeri with a broken and vestigial lateral carina also arising from each humeral angle and proceeding to about the position normally occupied by the metanotal groove (here absent). The species has been collected at just two sites on the east coast of Madagascar in Toamasina Province. The queens of this species are similar to small queens of S. hildebrandti, but the propodeum is uniformly striolate and the mesoscutum is low and flat, so that the pronotum is clearly visible in dorsal view.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  gongromos. Monomorium gongromos Heterick, 2006: 169, figs. 27, 80 (w.q.) MADAGASCAR. Combination in Syllophopsis: Ward et al., 2014: 13.

Worker
Holotype: HML 1.55 HL 0.56 HW 0.47 CeI 84 SL 0.40 SI 85 PW 0.36.

HML 1.36–1.67 HL 0.51–0.58 HW 0.41–0.50 CeI 80–86 SL 0.36–0.42 SI 84–90 PW 0.30–0.39 (n=20).

HEAD: Head rectangular; vertex planar or weakly concave; frons shining and smooth except for piliferous pits; pilosity of frons a mixture of incurved, semi-erect setae and slightly shorter decumbent setae; Eye small, eye width less than 1× greatest width of antennal scape; (in full-face view) eyes set at about midpoint of head capsule; (viewed in profile) eyes set posteriad of midline of head capsule; Eye elliptical, curvature of inner eye margin may be more pronounced than that of its outer margin. Antennal segments 12; antennal club three-segmented. Clypeal carinae always well-defined; anteromedian clypeal margin emarginate, clypeal carinae terminating in blunt angles, or, emarginate, clypeal carinae terminating in small denticles; paraclypeal setae moderately long and fine, curved; posteromedian clypeal margin extending slightly beyond level of posterior margin of antennal fossae. Anterior tentorial pits situated nearer antennal fossae than mandibular insertions. Frontal lobes sinuate, divergent posteriad. Psammophore absent. Palp formula 2,2. Mandibular teeth four; mandibles linear-triangular and smooth (except for piliferous pits); masticatory margin of mandibles strongly oblique; basal tooth approximately same size as t3 (four teeth present).

MESOSOMA: Promesonotum shining and smooth on dorsum, entire lower mesopleuron distinctly striolate; (viewed in profile) curve of anterior promesonotum abrupt, flattened or gently convex thereafter, promesonotal humeri with small tubercle or rugosity when seen in full-face view; promesonotal setae greater than twelve; standing promesonotal setae consisting of a mixture of incurved, semi-erect setae and slightly shorter decumbent setae; appressed promesonotal setulae few, mainly on sides of promesonotum. Metanotal groove absent. Propodeum shining, dorsum and sides of propodeum mainly smooth, with weak to strong striolae on declivitous face and on metapleuron; propodeal dorsum sloping posteriad, and depressed between raised propodeal angles; propodeum distinctly angulate, propodeal angle sharp; length ratio of propodeal dorsum to its declivity about 3:2; standing propodeal setae consisting of two or more prominent pairs anteriad, often with another pair of prominent setae posteriad, and other smaller setae on/around dorsal and declivitous surfaces of propodeum; appressed propodeal setulae very sparse or absent; propodeal spiracle nearer declivitous face of propodeum than metanotal groove. Vestibule of propodeal spiracle distinct in some specimens. Propodeal lobes present as blunt-angled flanges.

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated slightly anteriad of petiolar node, or, lateral and situated within anterior sector of petiolar node; node (viewed in profile) subcuboidal, inclined posteriad; appearance of node shining and smooth throughout; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) about 1:1; anteroventral petiolar process present as a thin flange tapering posteriad; ventral petiolar lobe present, but weakly developed to vestigial; height ratio of petiole to postpetiole about 4:3; height–length ratio of postpetiole between 4:3 and 1:1; postpetiole shining and smooth; postpetiolar sternite depressed at about its center, with anterior process developed as a short, conspicuous spur angled at 45–90.

GASTER: Pilosity of first gastral tergite consisting of a mixture of incurved, semi-erect setae and slightly shorter decumbent setae.

GENERAL CHARACTERS: Color of head, appendages and node yellow, mesosoma light orange to brick red, gaster yellowish-brown. Worker caste monomorphic.

Queen
HML 2.26–2.29 HL 0.65 HW 0.62–0.63 CeI 95–97 SL 0.49–50 SI 78–79 PW 0.59–0.64 (n=2).

HEAD: Head square; vertex weakly concave or planar; frons longitudinally striolate medially, sides of head capsule shining and smooth; pilosity of frons a mixture of well-spaced, distinctly longer erect and semi-erect setae interspersed with shorter setae or setulae, which are decumbent or appressed, longer setae thickest on vertex. Eye ovoid, narrowed posteriad; (in full-face view) eyes set at about midpoint of head capsule; (viewed in profile) eyes set posteriad of midline of head capsule.

MESOSOMA: Mesoscutum broadly convex anteriad, convexity reduced posteriad; pronotum, mesoscutum and mesopleuron shining and mainly smooth, vestigial striolae, if present, confined to anterior katepisternum; length–width ratio of mesoscutum and scutellum combined between 2:1 and 3:2; axillae separated by width of at least one axilla; standing pronotal/mesoscutal setae consisting of a mixture of incurved, semi-erect setae and slightly shorter decumbent setae; appressed pronotal, mescoscutal and mesopleural setulae few, mainly on sides of pronotum and mesopleuron. Propodeum shining and densely striolate over whole surface; propodeum distinctly angulate, propodeal angle sharp; propodeal dorsum sloping posteriad, and depressed between raised propodeal angles; standing propodeal setae consisting of up to a dozen or more longer erect and shorter sub-erect setae; appressed propodeal setulae well-spaced and sparse; propodeal spiracle equidistant from metanotal groove and declivitous face of propodeum; propodeal lobes present as bluntly angled flanges.

WING: Wing not seen (queens dealated).

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated slightly anteriad of petiolar node; node (viewed in profile) cuneate, vertex tapered; appearance of node shining and weakly striolate posteriad; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) between 3:2 and 4:3; anteroventral petiolar process present as a thin flange tapering posteriad, or, absent or vestigial; height ratio of petiole to postpetiole between 4:3 and 1:1; height–length ratio of postpetiole about 4:3; postpetiole smooth anteriad, rugose posteriad; postpetiolar sternite depressed at about its center, with anterior process developed as a short, conspicuous spur angled at 45–90.

GASTER: Pilosity of first gastral tergite consisting of a mixture of incurved, erect and semi-erect setae and slightly shorter decumbent setae.

GENERAL CHARACTERS: Color variegated brown and orange. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Type Material
HOLOTYPE: worker, Prov. Toamasina, F. C. Sandranantitra 18º02′9″S, 49º05′5″E 450 m 18–21.i.1999 H.J. Ratsirarson 101(11)–51/sifted litter rainforest. PARATYPES: Prov. Toamasina (specimens with same collection data as holotype): 3 workers 12 workers + 3 workers ; 4 workers (CAS); 22 workers + 12 queens + 1 worker.

Etymology
Greek ‘gongros’ (masc. ‘excrescence’) + ‘omos’ (masc. ‘shoulder’)