Thinophilus variabilis Samoh, Satasook & Grootaert, 2017

Grootaert, Patrick, 2018, Revision of the genus Thinophilus Wahlberg (Diptera: Dolichopodidae) from Singapore and adjacent regions: A long term study with a prudent reconciliation of a genetic to a classic morphological approach, Raffles Bulletin of Zoology 66, pp. 413-473 : 464-467

Thinophilus variabilis Samoh, Satasook & Grootaert, 2017

(Fig. 54)

Thinophilus variabilis Samoh, Satasook & Grootaert, 2017: 30 (Figs. 36–40).

Diagnosis. Medium-sized species (body 2.7 mm; wing 2 mm) with yellowish brown to brown fore coxa bearing long black bristles. Fore femur with a row of long posteroventral bristles over the entire length. Fore tibia with a row of long ventral spine-like bristles over entire length of tibia. Wing brownish.

Description. For a detailed description and images of the male and female, I refer to the description given in Samoh et al., 2017.

Remarks. The colour patterns in Thinophilus variabilis are quite variable and different between male and female. There are populations in southern Thailand in which the fore coxa in male and female are completely yellow, but other where the male has entirely yellow fore coca while the female has almost entirely black fore coxa (Samoh, in litteris).

Thinophilus variabilis is very similar to Thinophilus minor sp. nov., but they have quite a number of different characters.

Fig. 54. Thinophilus variabilis Samoh, Satasook & Grootaert, 2017 (Photo: A. Samoh).

They share the long ventral bristles on the fore tibia, that are long over the entire length of the tibia in T. variabilis while only in the apical ¾ in minor sp. nov. T. variabilis has a row of rather strong posteroventral bristles on the fore femur that are as long as the femur is wide. T. minor has only one distinct preapical posteroventral on the fore tibia. If there are a few other posteroventral bristles they are short and fine. In T. variabilis the fore tibia bears a anterodorsal and a posterodorsal bristle at the basal quarter while in T. minor sp. nov. there is only a short dorsal bristle in basal quarter.

The male terminalia are similar in both species. Although various morphological features are distinctly different, the NGS barcode of T. variabilis and T. minor sp. nov. are the same. Despite the equal barcodes, I consider them as two different species. It is the first case in a sample of more

Fig. 55. Thinophilus yeoi sp. nov., male habitus.

Fig. 57. Thinophilus yeoi sp. nov.: Phenology during a 2-year survey (MIP).

Etymology. The present species is dedicated to the late K.L. Yeo, who accompanied and helped us every week in the field collecting of the Malaise traps samples during the whole year of our sabbatical stay in Singapore in 2005.

Fig. 56. Thinophilus yeoi sp. nov., male. A, Detail of tip epandrium and epandrial lobe; B, Epandrium ventrally; C, Epandrium and cercus laterally; D, Cerci dorsally.

than 200 dolichopodid species in Southeast Asia where the non-genitalic morphology of two species is distinct, while their male terminalia and DNA barcodes are similar but not congruent with the morphology.

Distribution. Very common in southern Thailand. Not found yet in Singapore.