Rhabdomastix (Rhabdomastix) incapax Stary , 2005

Stary, Jaroslav & Rohacek, Jindrich, 2015, Rediscovery of Rhabdomastix (Rhabdomastix) incapax Stary, 2005 (Diptera, Limoniidae), a crane fly species flightless in both sexes and probably endemic to Sardinia, ZooKeys 498, pp. 93-101 : 94-96

Taxon classification Animalia Diptera Limoniidae

Rhabdomastix (Rhabdomastix) incapax Stary, 2005 Figs 1-3, 4-5, 8-9

Rhabdomastix (Rhabdomastix) incapax Starý 2005: 490 (original description), Figs 1 (general view), 2 (male antenna), 3 (male palpus), 4 (male terminalia).

Description of male.

In general, the male was adequately described structurally in the original description. In contrast to the holotype, which was described as dirty yellow due to the teneral state and preservation in ethanol, the body of the fully-emerged specimen is shiny black throughout, with only bases of the wing rudiments and bases of the halteres light orange-yellow (Figs 4-5, 8-9). In dry-mounted material, the bases of the wings and halteres are darker and less conspicuous. Whereas the body, especially the abdomen, becomes somewhat wrinkled in dry-mounted specimens, in material preserved in ethanol an opposite process often occurs. This may change proportions and measurements from what was stated in the original description. The measurements of the holotype were given as follows: body length 4.0 mm, wing length 1.5 mm, antenna 2.5 mm ( Starý 2005: 490). We here give the measurements based on dry-mounted males (see Material examined): body length 2.7-3.6 mm, wing length 1.4-1.8 mm, antenna 2.3-3.0 mm. For a better idea of live specimens, Figs 4-5, 8-9 should be consulted. Wing and wing venation of the male were partly described in the original description. The male wing is here illustrated (Fig. 1), with emphasis on the fact that veins R5 and M1+2 have a few macrotrichia dorsally and vein A2 is apparent. As described for the female below, the whole abdomen of the male is likewise densely covered with well-developed, spinoid microtrichia, not only segment 9 and the gonocoxite, as follows from the original description.

Description of female.

In general appearance resembling male. Body length 3.1-3.5 mm, wing length 0.9-1.3 mm, antenna 1.0-1.1 mm (dry-mounted specimens).

Head. Antenna 15-segmented, considerably shorter than that of male, reaching to base of halter (Figs 8-9), distinctly longer than antenna of most other European Rhabdomastix (Rhabdomastix) females [except for female Rhabdomastix (Rhabdomastix) hirticornis (Lackschewitz, 1940), subequal in length of antenna to female Rhabdomastix (Rhabdomastix) incapax ]. Flagellomeres from ovoid to long-ovoid, gradually narrowed towards apex of antenna. Verticils on flagellomeres sparse, more or less decumbent, shorter than respective segments. Palpus short, as in male (cf. Starý 2005, Fig. 3).

Thorax slender as in male, with only a few short setae dorsally. Wing as in male (cf. Fig. 1) including venation, only slightly shorter and narrower (Figs 8-9), in general very dark to blackish, obscure yellow at base in dry-mounted specimens. Halter as in male, reaching to about half length of abdominal segment 2, obscure yellow at base, otherwise dark. Legs shorter than those of male, femora somewhat thickened distally, length ratio of male and female femur about 1.2: 1.

Abdomen slightly stouter than in male, with only rows of short setae along posterior, and partly lateral, margins of segments as in male, and densely covered with well-developed, spinoid microtrichia, both on sclerites and membranes, except for cercus and hypogynial valve. Female terminalia (Figs 2-3). Cercus slender, gently upturned, slightly longer than tergite 10. Hypogynial valve extending to about one third length of cercus. Internal structures much as in other European Rhabdomastix (Rhabdomastix) species (cf. Starý 2004), differing only in details. Infra-anal plate slender, strongly arched, more or less horseshoe-shaped, with several setae at posterior margin; sternite 9 membranous, little-distinct, generally triangular; genital fork (vaginal apodeme) comparatively slender and long, with darkened edges; spermathecae three, darkly pigmented, medium-sized, long-ovoid to reniform, somewhat narrowed in portion closer to duct, practically without sclerotized parts of ducts (Figs 2-3).

Material examined.

Italy: Sardinia (north-east): Monti, 8.1 km S, Rio de s’Éleme, road bridge (riverside vegetation), 465 m, 40°44'N, 9°22'E (Figs 6, 7, 10), 7.v.2014, 3 ♂, 1 ♀, 12.v.2014, 24 ♂, 2 ♀ (J. Roháček & J. Starý leg.); Mazzinaiu nr. Alà dei Sardi, 6.6 km NE, marshy vegetation along brook, 508 m, 40°45'N, 9°25'E (Fig. 11), 7.v.2014, 1 ♂ (M. Vála leg.) (all in coll. J. Starý, Olomouc, Czech Republic).

Discussion.

Noticeably, Rhabdomastix (Rhabdomastix) incapax is the only species among European Rhabdomastix with reduced wings. The shiny black body colouration is another distinguishing character evident at first sight. The female antennae of Rhabdomastix (Rhabdomastix) incapax are longer than those of females of the majority of other species. Rhabdomastix (Rhabdomastix) hirticornis is the single other European species that has conspicuously sexually dimorphic antennae, corresponding in length, relative to the size of the species, to those of Rhabdomastix (Rhabdomastix) incapax . Female terminalia of the latter species are of general structure usual for Rhabdomastix (Rhabdomastix) , the most indicative character being the shape of the spermathecae, which are considerably elongate (Figs 2-3, for various details in other species, see figures in Starý 2004, 2005).

Distribution.

Italy: Sardinia. Considering the flightlessness of Rhabdomastix (Rhabdomastix) incapax and, consequently, its very limited dispersal abilities, the species is most probably endemic to the island.