Atrichopogon (Borkent & Picado, 2004)

Borkent, Art, 2024, The Phylogeny of the Genera of Biting Midges (Diptera: Ceratopogonidae) of the World, Zootaxa 5438 (1), pp. 1-274 : 222-223

Atrichopogon :

- Female without torma. Gad (1951) first pointed out this feature. Whether it is truly unique is questionable because the torma is difficult to identify in many genera of Ceratopogonidae .

- Paratergite large and bearing at least one large seta. The feature is unique among other Culicomorpha and the early lineages of Ceratopogonidae ( Leptoconopinae , Forcipomyiinae , Culicoidini , Ceratopogonini ) but is superficially similar to the large paratergite of higher lineages, further discussed under character 70.

- Foretibia curved anteroposteriorly for about basal 1/3. This feature is unique in the Culicomorpha but can only be seen in material that isn’t slide mounted and where the foretibia can be viewed dorsomedially. As such, I was unable to examine enough material to ensure that it is an autapomorphy of the entire genus.

For the few species for which mating has been observed, members of this genus have a unique mating position with the male above the female with both facing the same direction and then the male often falling backward and facing upward ( Downes 1955, 1978; Dettner 1997). In all other observed (limited) Ceratopogonidae the mating position is with both standing end to end. Most other Culicomorpha mate end to end, although Simuliidae and Thaumaleidae mate with the male above the female, likely an independent synapomorphy of these two families (only one mated pair of Thaumaleidae has been observed, with the male on his back behind the female ( Borkent et al. 2008a), similar to some Simuliidae and Atrichopogon due to the male losing grip of the female as noted above).

Although the curved foretibia is present in both male and female Atrichopogon , it is possible that the curved foretibia is related to the dorsally positioned male needing to grasp the female thorax at least in the initiation of copulation (at least sometimes with the male later falling backward on to its back), with the feature in the female being a result of retention of a male-selected feature.

Downes (1978: 46) states that male Atrichopogon bring their genitalia downwards and forwards to bring their ventrum to the ventrum of that of the female. Considering that male Atrichopogon do not rotate their genitalia, this is likely a misinterpretation and the ventrum of the male genitalia is actually in contact with the dorsum of female genitalia, as more accurately described by Downes (1955) and as in all other Culicomorpha.

- Male with the parameres and ventral plate difficult to distinguish, forming what was previously called the aedeagal/ parameral complex ( Borkent & Picado 2004) and here renamed the parameral/ventral plate complex, unique within the Culicomorpha. It is uncertain whether this fusion applies to all species of the genus and further study is warranted. Further to this, it is uncertain how this complex might function, considering the gonopore lies between the parameres and ventral plate in other Ceratopogonidae ( Pomerantsev 1932) .