Trichomyrmex robustior ( Forel, 1892 )

Mostafa R. Sharaf, Shehzad Salman, Hathal M. Al Dhafer, Shahid A. Akbar, Mahmoud S. Abdel-Dayem & Abdulrahman S. Aldawood, 2016, Taxonomy and distribution of the genus Trichomyrmex Mayr, 1865 (Hymenoptera: Formicidae) in the Arabian Peninsula, with the description of two new species, European Journal of Taxonomy 246, pp. 1-36 : 26-28

Trichomyrmex robustior ( Forel, 1892)

Fig. 12 A–C

Monomorium (Parholcomyrmex) gracillimum robustior Forel, 1892 : Afrotropic. Lectotype, worker (CASENT0101849) (MHNG) [examined].

352

(workers).

Somalia.

Monomorium (Parholcomyrmex) robustior – Emery 1893: 256. — Forel 1894b: 228.

Trichomyrmex robustior – Ward, Brady, Fisher & Schultz 2015: 16. — Heterick 2006: 99 (lectotype designation).

Material examined

Previous records

OMAN: AI-Khuwayr, 23.59˚ N, 58.41˚ E, Sep. 1989, M.D. Gallagher leg.

SAUDI ARABIA: Wadi Al-Ammariyah, 24.81˚ N, 46.44˚ E, alt. 696 m, Dec. 1977, W. Buttiker leg.

YEMEN: Wadi Surdud, 15.26˚ N, 43.71˚ E, 29 Dec. 1991, A.V. Harten leg.

Description of large worker

MEASUREMENTS. TL 2.5–3.4; HL 0.68–0.84; HW 0.62–0.78; SL 0.52–0.66; PW 0.36–0.46; ML 0.70–0.92;

CI 90–97; SI 82–88 ( Bolton 1987).

HEAD. With feebly convex sides and slightly concave or emarginated posterior margin in full-face view; in some individuals head broader anteriorly than posteriorly; anterior clypeal margin nearly straight or shallowly concave; basal mandibular tooth reduced to minute denticle; eyes of moderate size (EL 0.18–0.20 × HW), situated just in front of midline of head and with 6–8 ommatidia in longest row; scapes when laid back from their insertions just reach posterior margin of head.

MESOSOMA. Promesonotum domed in profile; metanotal groove impressed; propodeal dorsum on a lower level than that of promesonotum in profile.

PETIOLE. Peduncle elongate, petiolar node strongly rounded in profile.

POSTPETIOLE. Node at a much lower level than that of petiole in profile.

PILOSITY. Underside of head with few short straight hairs, not forming a psammophore; cephalic surface with long fine decumbent to appressed pubescence directed toward midline of head; mesosomal dorsum with long erect to suberect hairs and abundant appressed pubescence; petiole, postpetiole, first gastral tergite and sternite with numerous long curved backward directed hairs and with sparse appressed pubescence.

SCULPTURE. Mandibles longitudinally rugulose, cephalic dorsum and sides of promesonotum smooth and shining; metapleuron and propodeal sides regularly punctulate-reticulate; propodeal dorsum finely transversely rugulose; petiole, postpetiole and gastral tergites entirely smooth and shining.

COLOUR. Dark brown or blackish brown; gaster usually darker than head and mesosoma.

Differential diagnosis

The most similar species to T. robustior is T. mayri from which it can be separated by the smooth posterior margin of the head, the strongly convex promesonotal outline, the coarse and broadly spaced propodeal sculpture, and the longer and strongly curved body pilosity.

Distribution

This species was described from Somalia and recorded from Kenya and Madagascar ( Bolton 1987). Trichomyrmex robustior has been recorded from Saudi Arabia, Oman and Yemen ( Collingwood & Agosti 1996).

Figures

Fig. 12. Trichomyrmex robustior (Forel, 1892), lectotype, worker (CASENT 0101849). A. Body in profile. B. Body in dorsal view. C. Head in full-face view (photos: Zach Lieberman).