Mystrium camillae Emery

Mystrium camillae Emery

Fig. 1–3, 10, 13

Mystrium Camillae [sic] Emery, 1889: 491, pl. 10, figs. 1–3. Syntype worker and queen: Myanmar (as “ Birmania ”: Bhamò (Fea) [MCSN] (not examined; photographs of syntype worker and queen examined on AntWeb (www.antweb.org): CASENT0102123 (worker), CASENT0102124 (queen)).

Mystrium camillae Emery subsp. javana Karawaiew, 1925: 73, figs. 1 & 2. Syntype worker: Java, limestone mountain near Tjampea, no. 2389, 2 workers on the ground, under leaves (Karawaiew) (not examined). Synonymy by Brown, 1960: 170.

Mystrium camillae; Menozzi, 1929: 535 –536, fig. 9. Revision of the genus and key to species.

Mystrium oculatum Xu, 1998: 161, figs. 1 & 2. Holotype worker: China: Yunnan Province, Mengla County, Menglun Town, Bakaxiaozhai (Xu Zheng-hui) [SWFC] (not examined; photographs of paratype examined on AntWeb (www.antweb.org): CASENT0104982 (worker)). New synonymy.

Material examined. Indonesia: Sumatra: Lampung, Tulang Bawang, Gn. Tanggang, 05°43.933' S, 105°06.598' E, 580m (1 worker, 9.VIII.2006, A. Riedel) [SMNK]; Sumatra: Lampung, Tulang Bawang, Gn. Tanggang, 05°43.938' S, 105°06.440' E, 580m (5 workers, 9.VIII.2006, A. Riedel) [SMNK]; Java: Jawa Barat, Ciamis, Gn. Sawal, Batu Cakra, 07°14'55'' S, 108°15'46'' E, 990m (1 worker, 1.X.2005, A. Riedel) [SMNK]. MALAYSIA (WEST): Negri Sembilan, Simpang Pertang, Pasoh Forest Reserve, 02°59' N, 102°19' E (1 worker, 29.III.1992, K. Rościszewski) [SMNK]; MALAYSIA (WEST): Terengganu, Lake Kenyir, 04°58' N, 102°49' E, 300–400m (22 workers, 7.–12.VII.2001, A. Schulz) [SMNK].

Measurements and indices. Workers: HL 0.81–1.75, HW 0.85–1.64, CI 88–105, SL 0.50–1.00, SI 54– 64, ML 0.52–1.75, WL 0.91–1.49, PW 0.47–0.80 (n = 31).

Diagnosis (worker). The following character combination differentiates M. camillae from all its congeners in the Indo-Australian region: the apex of each mandible distinctly expanded and rounded in lateral view, with a more or less triangular and caudally directed tip on the inner side; outer face of labrum entirely covered with a weakly developed, irregular rugoreticulum; maxillary palps 4-segmented; the second segment of the maxillary palp shorter than the basal (first) segment and less than half as broad as the basal segment; antennal segment III shorter than twice its width; each anterolateral corner of the head produced into a short, nearly triangular, pointed spine; dorsum of head with rugose-reticulate cuticular sculpture and spatulate hairs; minute compound eyes; petiolar node not broader than twice its length measured in dorsal view.

Distribution. Widely distributed in the Indo-Australian region and neighboring countries. Recorded from Australia, Brunei, China, India, Indonesia, Malaysia, Myanmar, Papua New Guinea, the Philippines and Singapore.

Comments. Brown (1960, p. 170) gave no justification for the synonymy of M. camillae subsp. javana under M. camillae but the differences between the taxa given in the description of Karawaiew (1925) fall within the variation of the senior synonym. The most important difference between the taxa — the shape of the mandible apex — depends on the angle from which the mandible is viewed. The triangular tip is highly variable in the specimens examined and often worn out. The number of truncated teeth at the anterior clypeal margin varies from 6–7 in the specimens we have seen and thus is not a character to distinguish the taxa. In most cases there is a toothless gap between the left and right group of these teeth (but see the specimens from Northern Australia depicted on AntWeb [CASENT0172841, CASENT0172082]. From Karawaiew’s description it is clear that he never had a specimen of M. camillae at hand but made his judgment of the species just from the description and the drawings of Emery (1889).

Xu (1998: 161, figs. 1 & 2) notes in his description of M. oculatum that this species is close to M. camillae but differs from it by: “small eyes present; central dorsum of hat flat; metanotal groove only shallowly depressed; declivity of propodeum flat, not depressed; anterodorsal angle of petiolar node more extruding.” All examined specimens of M. camillae possess minute compound eyes. The presence of eyes was already noted in the original description of M. camillae by Emery (1889) and again in Menozzi’s revision. Therefore, the presence of eyes in M. oculatum cannot be regarded as a diagnostic character to distinguish it from M. camillae. All other diagnostic characters given for M. oculatum by Xu vary much among individuals of M. camillae. The morphology of M. oculatum as described by Xu (1998: 161–162, figs. 1 & 2) and shown by photographs of a paratype of M. oculatum on AntWeb (www.antweb.org: CASENT0104982) falls well within the range of morphological variation exhibited by the examined specimens of M. camillae. Additionally, all but one metric character of M. oculatum fall into the range of M. camillae. The exception is CI, which is slightly higher.