Myrmicaria transversa, Zettel & Laciny & Balàka & General, 2018

Zettel, Herbert, Laciny, Alice, Balàka, Pia & General, David Emmanuel M., 2018, On the taxonomy of Myrmicaria Saunders, 1842 (Hymenoptera: Formicidae) in the Philippines, Raffles Bulletin of Zoology 66, pp. 610-623 : 618-622

Myrmicaria transversa new species

( Figs. 13–16 , 20 )

Etymology. Named after the characteristic transverse keel on the propodeum.

Material examined. Holotype (worker) ( NMNH) from Luzon Island, Sorsogon Province, San Roque, Palok Tok Falls , 26 February.

Paratypes: 6 workers ( NHMW, CZW) from the same locality .

Diagnosis (worker). Clypeus with pronounced median carina. Scape long, SI = 104–110. Sides of mesonotum angularly elevated; posterior surface with reduced sculpture; posterior margin convex. Rugae on metapleura and sides of propodeum reduced. Propodeal spines moderately long, directed caudally, continuing dorsal outline of propodeum. Propodeum deeply furrowed between bases of spines. Peduncle of petiole moderately long. Base of gaster tergite 1 without striation. Gaster usually completely infuscated.

Description (worker). Measurements of holotype: HW 1.34; HL 1.29; SL 1.46; SW 0.15; TL 5.87; Pmin 0.14; PW 0.36; PPW 0.39; SpD 0.37; PrL 0.87; FeL 2.02; ML 1.73; PnW 0.85; CI 103; SI 109; FeI 151.

Measurements of paratypes: min–max (n = 6): HW 1.25–1.46; HL 1.20–1.43; SL 1.37–1.54; SW 0.14–0.16; TL 5.51–6.20; Pmin 0.13–0.17; PW 0.33–0.40; PPW 0.36–0.44; SpD

0.29–0.36; PrL 0.78–0.90; FeL 1.86–2.12; ML 1.63–1.89; PnW 0.78–0.95; CI 102–105; SI 104–110; FeI 143–153.

Structures: Head ( Fig. 15 ) roundish, hardly wider than long; medioposteriorly with strong piliferous punctures; dorsal and lateral areas with longitudinal rugae. Clypeus with pronounced complete median carina and few longitudinal rugae. Mandible with sharp longitudinal rugae; apical margin with four teeth. Mesosoma with a median carina starting from anterior third of pronotum, reaching posterior fourth of mesonotum. Pronotum with transverse rugae in anterior third, and longitudinal rugae in posterior two thirds; anteroventral teeth short, hardly protruding at sides. Mesonotum, in addition to median carina, with a strongly developed transverse carina at mid-length; anteriorly with an additional transverse carina, sometimes rather reticulated, posteriorly with or without additional longitudinal rugae; sides strongly elevated. Metanotal groove narrow and deep; in dorsolateral view, lateral margin forming an acute angle. Pro- and mesopleura with longitudinal rugae, metapleura and sides of propodeum almost smooth. Dorsum of propodeum with reduced sculpture, except for a distinct transverse carina anteriorly; area between bases of spines deeply impressed. Propodeal spines moderately long and straight, directed caudally, slightly diverging, at base continuing dorsal outline of propodeum. Nodes of petiole and postpetiole rounded; peduncle of petiole moderately long. Gaster with piliferous punctures; base of gaster tergite 1 without striation.

Setae abundant on trunk and appendages. Dorsal setiferation composed of two types of setae, short setae about half as long as long ones. On dorsum of head, petiole and postpetiole all setae suberect. On gaster, long setae suberect, short setae subdecumbent anteriorly, suberect posteriorly.

Colour: Head medium brown, dorsally infuscated in some specimens. Mesosoma and nodes of petiole and postpetiole light brown; peduncle of petiole contrasting yellow. Gaster dark brown, almost black. Antenna yellow. Legs very light brown. All setae whitish.

Comparative notes. Myrmicaria transversa new species differs from most Philippine species (described and undescribed) by the transverse carina on the dorsal surface of the propodeum ( Fig. 20 ). In M. aphidicola and M. buenaventei new species, such a carina or short fractions of it are occasionally present, but M. aphidicola differs by the basal striation of the gaster and M. buenaventei new species has a very differently sculptured pronotum, prominent pronotal teeth, and short scapes. The reduced sculpture of the mesonotum, metapleura, sides of propodeum, and base of gaster place M. transversa new species in close relationship to a hitherto undescribed species from Luzon and Catanduanes. That species, however, is more gracile and possesses slightly upcurved propodeal spines and a relatively long petiolar peduncle.

Distribution. Although the genus is widespread in the southern part of Luzon Island (Bicol Region), this species has only been found at the type locality in Sorsogon Province.

Figures

Figs. 13–14. Holotype worker of Myrmicaria transversa new species in lateral (13) and dorsal (14) view.

Figs. 15–16. Holotype worker of Myrmicaria transversa new species: (15) head in full-face view; (16) postpetiole and base of gaster tergite 1 in dorsal view.

Figs. 17–20. Mesosoma in dorsal view: (17) Myrmicaria aphidicola from Bukidnon; (18) M. buenaventei new species (holotype); (19) M. chapmani new species (holotype); (20) M. transversa new species (holotype).