Crematogaster (Crematogaster) fraxatrix Forel

Hosoishi, Shingo & Ogata, Kazuo, 2014, Description and DNA barcoding of Crematogaster fraxatrix Forel, 1911 and two new closely related species from Cambodia and Indonesia (Hymenoptera, Formicidae), ZooKeys 374, pp. 57-68 : 62-63

Crematogaster (Crematogaster) fraxatrix Forel Figs 3-6

Crematogaster fraxatrix Forel, 1911: 28 Worker syntypes from MALAYSIA: Sarawak, Borneo ( Haviland ) [MHNG, NHMB, examined]. Combination in Crematogaster (Acrocoelia) : Emery 1922: 151; in Crematogaster (Crematogaster) : Bolton 1995: 166; Blaimer 2012b: 55.

Type material examined.

MALAYSIA: Sarawak, Borneo (Haviland). Lectotype worker by present designation: top specimen of three specimens of one pin.

Other material examined.

THAILAND: 5 workers, Khlong Klai Stn., Khao Nan N. P., Nakhon S. Thamarat, 13.iii.2007 (TH07-SKY-22) (Sk. Yamane); MALAYSIA: 2 workers, Ulu Gombak, Selangor, 09.iii.2009 (SH09-Mal-51) (S. Hosoishi); 2 workers, Mt. Ophir, Gunung Ledan, Johor, 11.x.2011 (SH11-Mal-47) (S. Hosoishi); 3 workers, Lambir Hill’s National Park, Borneo, 21-27.ii.2009 (Y. Hashimoto).

Measurements and indices.

HW 0.7-0.98; HL 0.64-0.93; CI 105-114; SL 0.58-0.68; SI 69-91; EL 0.13-0.18; PW 0.37-0.62; WL 0.69-0.95; PSL 0.13-0.21; PtL 0.18-0.25; PtW 0.18-0.25; PtH 0.13-0.17; PpL 0.11-0.15; PpW 0.16-0.23; PtHI 65-74; PtWI 94-111; PpWI 123-155; WI 83-92 (thirteen workers measured).

Diagnosis.

This species is similar to Crematogaster chhangi , but can be distinguished by the oval-shaped propodeal spiracles and weakly developed subpetiolar process in the worker caste. Based on COI divergence, the specimens from Peninsular Malaysia were separated from the Bornean specimens with a high support value (Fig. 9). This is presumably due to lack of gene flow between the populations, but they showed no distinct morphological differences between each other. The COI divergence of 0-9.3% (K2P distances) was recorded within Crematogaster ranavalonae clade in Madagascar ( Blaimer 2012a). Further geographic sampling is therefore needed to determine whether the variation of 0.4-6.9% (K2P distances) represents the intraspecific variation or includes some interspecific variation.

Worker description.

Workers with weak polymorphism in size. Posterior corners of head rounded in smaller worker, but squared in larger workers. Anterior clypeal margin slightly concave in the median portion. Compound eyes not projecting beyond lateral margins of head in full face view. Scape reaching posterior corner of head. Antennal club 3-segmented. Pronotal dorsum with distinct ridges laterally. Mesonotal dorsum with lateral ridges. Mesonotum slightly higher than pronotum in larger workers in lateral view. Metanotal groove straight in dorsal view, deep and forming a concave region between mesonotum and propodeum. Propodeal spiracles dorso-ventrally oval, located on lateral sides of propodeum; the horizontal diameter slightly larger than the vertical diameter even in smaller workers. Propodeal spines long, directed upward and straight. Petiole broader in the middle portion. Subpetiolar process developed as small, blunt denticle. Postpetiole weakly bilobed, but without longitudinal median sulcus. Petiole slightly wider than postpetiole in dorsal view.

Sparsely hirsute with erect setae. Scape with abundant erect to suberect setae. Dorsal face of head with suberect setae. Clypeus with suberect setae; one pair of longer setae directed medially on anteriormost portion. Anterior clypeal margin with one single setae and one pair of longer setae, mixed with some shorter setae on the sides. Mesosoma with sparse erect setae. Fourth abdominal tergite with sparse erect to suberect setae.

Dorsal surface of head generally smooth and shining, but feeble rugulae between frontal carinae; longitudinal rugulae surrounding antennal sockets and on gena. Clypeus weakly striated with longitudinal rugulae. Pronotum striated with feeble rugulae. Mesonum weakly striated with feeble rugulae. Lateral surface of pronotum smooth and shining. Mesopleuron sculptured, but the central portion relatively smooth. Lateral surface of propodeum with feeble rugulae.

Body color reddish-brown to black.

Distribution.

This species is known from southern Thailand and Malaysia (Peninsular and Borneo).