Subgenus Scottiscydmaenus Franz

Scottiscydmaenus Franz, 1975: 277 (as subgenus of Scydmaenus). Type species: Scydmaenus lodoiceae Scott, 1922 (des. orig.).

Diagnosis. Franz (1975) defined Scottiscydmaenus by the following characters: (1) antennae with slender trimerous clubs with elongate antennomeres 9 (Fig. 127); (2) the pronotum strongly convex, lacking antebasal pits and a longitudinal carina (Fig. 125); (3) elytra strongly convex, lacking humeral calli and humeral folds (Fig. 130); (4) metanepisterna not demarcated from the metaventrite (Fig. 128); (5) the profemur in males with two ventral carinae, anterior one distally with a broad and blunt projection (Fig. 129); and (6) protibia in males distally weakly broadened, laterally flattened. The latter character was here found rather problematic, as the protibiae in all studied species are almost unmodified (Fig. 129).

Remarks. The status of Scottiscydmaenus as a separate subgenus will require verification. The Australian species share similarly modified profemora in males (with a distal anterior/dorsal tooth (Fig. 129)—the anterior/dorsal terminology refers to the femur observed in the position as in Fig. 130); antennae with conspicuously slender proximal flagellomeres and also a slender, elongate antennomere 9, so that the club appears as dimerous (Fig. 127); barely broadened protarsi in males with only sparse, poorly visible tenent setae (Fig. 129); pronota lacking pits (Fig. 125); elytra with reduced humeral structures (humeral calli, humeral folds, and basal impressions) due to lack of wings (Fig. 125); lack of lateral submental lobes (Fig. 126); the basisternal region of the prosternum distinctly, but not much longer than procoxal rests (Fig. 126); a narrow, almost carinate mesoventral intermesocoxal process (Fig. 128); metaventral intermetacoxal process about as wide as one metacoxa (Fig. 128); and the aedeagus in dorsal view narrowing distally, in lateral view weakly curved, lacking lateral subapical lobes, with dorsodistal minute setae and symmetrical ‘chambers’ of the proximal flagellar region (e.g., Figs 136–139). However, it is unclear if this set of characters is sufficient to define a separate subgenus.

Composition, distribution and biology. Scottiscydmaenus includes six valid species names, but two of them were found to be synonymous during the present study, and one more new species is described. This subgenus is distributed in Madagascar, Seychelles (Praslin), and continental Australia. The Australian species are relatively variable in the body length and proportions of body parts; the most stable features are the shape of the head and the profemoral tooth in males. Scydmaenus clarkianus Franz, S. brachyponerophilus sp. n. and S. swanensis have been collected from colonies of the ant Brachyponera lutea (Mayr); S. optatus Sharp from colonies of B. lutea and Rythidoponera victoriae (André) . It is possible that the relatively large variation in body size and proportions of body parts found among the Australian Scottiscydmaenus is due to a partial or complete genetic isolation of local populations living in fragmented habitats.

Identification key to males of Australian species of Scydmaenus (Scottiscydmaenus)

1 Head (together with mouthparts) clearly elongate........................................................... 2

- Head about as long as broad............................................................................ 3

2 Profemoral tooth sharp-angled and elongate; BL> 2 mm ..................... .. Scydmaenus brachyponerophilus sp. n.

- Profemoral tooth at most right-angled, broader than long or as long as broad; BL <2 mm ... Scydmaenus clarkianus Franz

3 Length of temple in dorsal view equal to about 3 × length of eye; body slender; aedeagus in dorsal view with subapical broadening as wide as sub-basal broadening................................................. Scydmaenus optatus Sharp

- Length of temple in dorsal view equal to about 2 × length of eye; body robust; aedeagus in dorsal view with subapical broadening narrower than sub-basal narrowing............................................ Scydmaenus swanensis Franz