Odontomachus rixosus

Identification
Key to Odonotomachus of the Indo-Australian Region

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Philippines, Singapore. Oriental Region: Bangladesh, Cambodia, India, Myanmar, Thailand. Palaearctic Region: China.

Nomenclature

 *  rixosus. Odontomachus rixosus Smith, F. 1857a: 64 (w.) SINGAPORE. Crawley, 1924: 388 (q.); Wheeler, G.C. & Wheeler, J. 1952c: 651 (l.); Imai, Brown, et al 1984: 67 (k.). Senior synonym of conifera, obscurior: Brown, 1976a: 105. See also: Brown, 1976a: 163; Sorger & Zettel, 2011: 157.
 * obscurior. Odontomachus rixosus var. obscurior Forel, 1900c: 58 (w.) MYANMAR. Viehmeyer, 1916a: 116 (q.). Junior synonym of rixosus: Brown, 1976a: 105.
 * conifera. Odontomachus rixosus var. conifera Forel, 1913k: 19 (w.q.) INDONESIA (Java). Junior synonym of rixosus: Brown, 1976a: 105.

Odontomachus rixosus

The specimen at labelled as “type” by Donisthorpe may not be so. One cannot be positive as there is no datum number on the disc of this specimen, which merely states “SING” (= Singapore). However, a specimen in, labelled “SING. 55/9” has the following information in Acc. Reg.: “1859 no. 9. Singapore (Malacca), purchased of Stevens. Collected by Mr A.R. Wallace.”

I suspect that this specimen may be the true holotype but have no way of conclusively proving it. The only evidence in support of this view is that in the original description of rixosus, Smith states that the thorax is “tranversely striated.” The specimen more or less fits this description, whereas the  specimen has weakly whorled, not transverse, striation on the pronotum.