Strumigenys cf. mutica (Brown, 1949) - New record

Tang, Kit Lam, Pierce, Mac P. & Guenard, Benoit, 2019, Review of the genus Strumigenys (Hymenoptera, Formicidae, Myrmicinae) in Hong Kong with the description of three new species and the addition of five native and four introduced species records, ZooKeys 831, pp. 1-48 : 28-30

Strumigenys cf. mutica (Brown, 1949) - New record Fig. 11 A–C

Material examined.

HONG KONG: Tai Po District, Ping Shan Chai, 22.486N, 114.187E, 142 m, 3.VI.2017 to 30.VI.2017, C. Barthélémy, ANTWEB1016246, Malaise trap, IBBL.

Measurements.

Alate females (n = 2): TL 2.2-2.5, HL 0.51-0.57, HW 0.39-0.41, MandL 0.13-0.14, SL 0.33-0.38, EL 0.14-0.16, PW 0.28-0.35, ML 0.58-0.68, PL 0.22-0.24, PH 0.19-0.20, DPW 0.13, PPL 0.11-0.13, GL 0.61-0.73, CI 72-76, MI 25, SI 85-92, OI 36-39, LPI 84-86, DPI 55-59.

This species is known in Hong Kong from two alate females. The shape of the mandibles, including the conspicuous diastema and dentition suggests that this species belongs to the S. mutica -group as defined by Bolton (2000). However, this species differs from other Asian species in this group, defined on the basis of the worker caste, by the absence of spatulate or spoon-shaped hairs, instead having elongate fine hairs covering the body. However, the queen caste of S. mutica was originally described as a separate species, Kyidris nuda ( Brown 1949), but then synonymized with S. mutica on the basis of complete nest series reared in laboratory conditions ( Brown 1952). The fine hairs on queens of S. mutica were described by Brown (1949) as short and pointed, which we confirmed after examination of photographs of the holotype of K. nuda ( Japanese Ant Image Database 2006, pictures PCD2228-48, 49 & 50). This is contrary to our specimens, which possess long suberect and erect fine hairs (Fig. 11 A–C). According to Brown (1949), queens of S. mutica also possess a densely punctulate-granulose mesonotal surface, while our specimens show a punctuate to finely strigate mesonotal surface, with shiny and smooth anepisternum and katepisternum. Unfortunately, we were not able to examine the queen specimen of S. mutica in great detail. While the specimens collected in Hong Kong might represent a new species within the S. mutica -group, we do not think that at this point enough evidence could be gathered to describe those as a new species. Future collection of workers or new available material of gynes collected in Taiwan or Japan might help solve this problem.

Ecology.

Very little is known about the ecology of S. mutica , as only two alate individuals collected in a secondary forest by Malaise traps are known (Fig. 10).

Comments.

Two species within the S. mutica -group have been recorded in nearby regions, S. mutica in mainland China (Guangxi, Hunan), Japan, South Korea, and Taiwan, and S. takasago , endemic to Taiwan. The latter species also differs from our specimens by its larger size (HL 0.70, HW 0.63), the conspicuous presence of erect spoon-shaped hairs on the body, and the acute propodeal declivity ( Terayama et al. 1995).