Trichadenotecnum imrum New & Thornton

(Figs 1D, 4, 5)

Trichadenotecnum imrum New & Thornton, 1976: 414 .

Specimens examined: [Singapore] 1 male, Bukit Timah forest, 24 hr survey, section trap 7–9 am, 26.x.1969, DHM (MHNG); 1 male 1 female, Bukit Timah forest, beating foliage, 1.xi.1981, DHM (MHNG) ; 1 male, Bukit Timah Nature Reserve, between Summit hut and Car Park, along Tangga Rengas trail, Rock Path and Lower Path, 110–140 m, beating, 17.xii.1987, CL (SEHU) .

Description of female genitalia. Egg guide long (Fig. 5A), much longer than basal width, slightly narrowing toward apex, distal margin only slightly arched, medially and laterally with longitudinal membranous regions; body of subgenital plate rather small, posterior margin with short and broad membranous region next to egg guide, anteromedially with broad membranous region. Gonapophyses (Fig. 5B). Ventral valve long; dorsal valve with long distal process; posterior lobe of external valve small. Spermapore plate (Fig. 5C) lightly pigmented anteriorly and around spermapore, symmetrical.

Remarks. The male specimens examined here match very well with the original description of this species, including genital structures (Fig. 4). This species was originally described from a single male from Selangor, Malaysia, and is here recorded from Singapore for the first time. The female of this species is described here for the first time.

This species is apparently closely related to T. cinnamonum but can be distinguished from the latter by the flattened epiproct (Fig. 4A), presence of the small projection placed left to the circular-plate on the hypandrium (Fig. 4C), and absence of the keel on the trichobothrial field (Fig. 4A) in male and the shape of the subgenital plate (Fig. 5A) in female. Furthermore, this species is very similar to T. felix in male and female genital structures, as also mentioned for T. cinnamonum . These three species apparently compose a monophyletic group within the corniculum group based on having the bifurcated posterior process on the phallosome (Figs 4D). They also share the following character state: the trichobothrial field is divided into two regions (Fig. 4A) (Thornton, 1961). The empty space of the trichobothrial field, observed in T. felix and T. imrum, corresponds to the keeled area of T. cinnamonum and other species of the corniculum group (Fig. 2A). As mentioned above, this situation strongly suggests that the presence of the trichobothrial process/keel is autapomorphic for the corniculum group and plesiomorphic within this group; its absence corresponds to an incomplete reversal leaving the empty area on the trichobothrial field (Fig. 4A).