A taxonomic revision of the Asian endemic subgenus Physocrema of the genus Crematogaster (Hymenoptera: Formicidae)

Abstract

The subgenus Physocrema of the genus Crematogaster is revised. Twelve species are recognized in the subgenus, of which two are new to science: C. (Physocrema) tanakai sp. nov. and C. (P.) yamanei sp. nov. An identification key based on the worker caste is provided. Taxonomic relationships between C. (P.) difformis and similar species are clarified. Crematogaster (P.) vacca Forel 1911 is raised to species level. The following new synonymies are proposed: C. (P.) inflata F. Smith 1857 = C. (P.) moorei Donisthorpe 1941 syn. nov.; C. (P.) mucronata Emery 1900 = C. (P.) fulmeki Forel 1922 syn. nov.; C. (P.) vacca Forel 1911 = C. (P.) stethogompha Wheeler 1919 syn. nov. = C. (P.) stethogompha detritinodis Wheeler 1919 syn. nov. Crematogaster (P.) onusta Stitz 1925 is referred to the subgenus Physocrema. C. tumidula Emery 1900 is transferred to the subgenus Oxygyne from Physocrema.

Functional morphology of the metapleural gland in workers of the ant Crematogaster inflata (Hymenoptera, Formicidae)

“…Cell counts for the metapleural gland in members of the congeners Crematogaster clariventris M ayr 1895 and Crematogaster depressa L atreille 1802 yield a total of 350 and 400 cells, respectively, which is among the highest known number among myrmicine ants (Fanfani & Giovannotti 1994). Members of the congeneric Crematogaster sewardi , which also belongs to the Physocrema group, also have enlarged metapleural glands (Maschwitz 1974; Hosoishi & Ogata 2009), but with total cell numbers of 747 and 774 in the two workers checked, their size is only half that of the glands of C. inflata . Maschwitz (1974) reported that the metapleural glands of C. sewardi (misidentified as Crematogaster difformis ) show the usual antibiotic function.…”

“…Estimation of the number of secretory cells was carried out by counting the cumulative number of cells occurring in serial sections through the entire thorax at 30‐μm intervals (which is the average cell diameter). Workers of Crematogaster sewardi (which, like C. inflata , belongs to the Physocrema group: Hosoishi & Ogata 2009), collected in the Bogor Botanical Gardens, Indonesia, were prepared the same way for comparison of the number of secretory cells in their metapleural glands.…”

“…In his 1974 paper, Maschwitz also included the congeneric species Crematogaster difformis S mith 1857, workers of which also have enlarged metapleural glands, but with the production of antibiotics as their main function. Crematogaster difformis is probably a mis‐identification of Crematogaster sewardi F orel 1901 (Hosoishi & Ogata 2009). As we had access to embedded material of C. sewardi , we also examined the metapleural gland of members of this species for comparison.…”

The metapleural gland of ants

“…Crematogaster ants in the subgenus Physocrema have hypertrophied MGs (Janet, 1898 b ; Donisthorpe, 1941; Hosoishi & Ogata, 2008, 2009), and MG secretions of Crematogaster difformis and Crematogaster inflata contain a mixture of phenolic compounds that are noxious to predators (Attygalle et al , 1989; Jones et al , 2005). When C. ( Physocrema ) inflata workers are attacked, they expel from the MG opening a droplet of a whitish, viscous, sticky secretion which they can retract back into the MG (Maschwitz, 1974; Buschinger & Maschwitz, 1984).…”

Systematics and biogeography of the ant genusCrematogasterLund subgenusOrthocremaSantschi in Asia (Hymenoptera: Formicidae)

“…The genus Crematogaster is one of the most diverse ant genera, particularly in the tropics (Hölldobler & Wilson, ). The regional‐scale taxonomy and systematics of the genus, which includes 487 valid species‐level names (Bolton, ) in two subgenera (Blaimer, 2012c, d), have received considerable attention in recent years (Longino, ; Hosoishi & Ogata, , ; Blaimer, , , ).…”