Tuesday, July 7, 2020

A new stalk-eyed fly: Teleopsis sorora

Stalk-eyed flies have eyestalks on which their eyes are mounted. These projections stick out from the sides of the head. Both males and females have eyestalks, but hey are much longer in males. Species are growing up to a cm in length and are known to feed on both decaying plants and animals.

Todays new species was found around Kandy, a major city in Sri Lanka. It is considered the sister species of Teleopsis ferruginea, hence the name sorora (sister).

For the experts: The literature on Sri Lankan Diopsidae is reviewed. Eight Diopsidae are now known to occur in Sri Lanka, five species in the genus Teleopsis and one species each in the genera Sphyracephala, Diopsis, and Cyrtodiopsis. The presence of Cyrtodiopsis requires confirmation to exclude the possibility of mislabelling. All five Teleopsis species are endemic, as are the Diopsis species and probably the Cyrtodiopsis species. Only Sphyracephala bipunctipennis Senior-White has a larger distribution as it also occurs in India. A key is presented for the Diopsidae of Sri Lanka. Three Teleopsis species were already known to occur in Sri Lanka: T. ferruginea Röder, T. krombeini Feijen and T. maculata Feijen. These species form the T. ferruginea species group. Two new species are now described for this group: Teleopsis neglecta sp. nov. and Teleopsis sorora sp. nov. Teleopsis ferruginea is redescribed, as an earlier redescription turned out to be based on a series of specimens of its sister species T. sorora sp. nov. The other three Diopsidae of Sri Lanka are listed and illustrated. Allometric aspects of the five Teleopsis species are discussed. Three Teleopsis species are sexually dimorphic with regard to eye span, while two species are monomorphic. It is assumed that sexual dimorphism developed independently in the T. ferruginea species group. This brings the number of known cases of independent development of sexual dimorphism in the Diopsidae to ten.

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