Catotrichinae, Edwards, 1938

Jaschhof, Mathias & Jaschhof, Catrin, 2008, Catotrichinae (Diptera: Cecidomyiidae) in Tasmania, with the description of Trichotoca edentula gen. et sp. n., Zootaxa 1966 (1), pp. 53-61 : 59-60

Characters of Catotrichinae

The redescription of extant Catotrichinae by Jaschhof (2001) is here supplemented and partly corrected.

Head. The anterior tentorial pits are very large. The frontal furrow, running from the mesal ocellus to the apex of the frons, is distinct throughout. The occipital furrow, running from the mesal ocellus to the occipital foramen, is evanescent towards the foramen. The number of ocelli is always 3; in Catotricha subterranea the mesal ocellus, described as being absent, is actually present though smaller than the lateral ocelli. Remnants of the larval stemmata are visible in at least two of the species, Catotricha subterranea and Trichotoca fraterna . The antennal flagellum of males bears setae gathered at the flagellomere base, and two kinds of supposed chemoreceptors intermingled and dispersed over all the flagellomere node: short hair-shaped translucent sensilla arising from ordinary pores and very long sensory hairs arising from hooded pores. Hairshaped translucent sensilla are also present on the flagellomere neck. The female antenna has basically 14 flagellomeres; in Catotricha subterranea flagellomeres are variously merged to minimally 9 fully separate ones, but the ordinary 14 also occur in this species. The clypeus is small and may be exceptionally ( Trichotoca edentula ) asetose. Stipites are traceable as two narrow sclerotized ribs. Cardo and lacinia are not traceable. The prementum is asetose, its apodemes are mesally fused to form a narrow rib with 2 posterior processes. Of the labellum the proximal segment is asetose, and the distal segment has setae on the outer surface and a line of prestomal teeth on the mesal surface.

Thorax. Two pairs of cervical sclerites are present, large laterocervicalia and tiny precervicalia. The antepronotum in Catotricha subobsoleta is setose, in the other species asetose. Mesanepisternum, mesopreepisternum, and metepisternm in Trichotoca fraterna are setose, otherwise asetose. The metanotum in Trichotoca spp. is setose, in Catotricha spp. asetose. Wing. The resting wings are held one upon the other flat above the abdomen. In two species, Catotricha subobsoleta and Trichotoca fraterna , setae on the costa between R5 and M1 are more sparse than elsewhere, by that indicating presence of a break; otherwise the costal break is absent. Legs. Femora, tibiae, and tarsi of Trichotoca spp. bear narrow scales in addition to ordinary setae. Pulvilli are present in one species, Catotricha marinae .

Preabdomen. Male sternite 1 is asetose, the other sclerites are setose. In females, sternum 1 is membranous and asetose, sternites 2 through 7 are progressively narrowed, and the sclerites of segments 6 through 8 are more weakly sclerotized than others. Spiracles are present generally on the pleural membrane of segments 1–7 in both sexes, and on segment 8 in female Catotricha subterranea . Terminalia. In males, sternite 9 is absent as a distinct sclerite; sternite 10 is very weak and closely attached to the cerci; and the cerci themselves are comparatively small and separated from tergite 9. The other male genitalic structures are quite diverse. In females, sternite 8 is strongly reduced, i.e. extremely narrow and asetose, the corresponding gonocoxites are large, setose and situated beneath tergite 9.

Discussion. Catotrichinae exhibit more plesiomorphous features than any other Cecidomyiidae , which is notably exemplified by the venation pattern and antenna structure ( Jaschhof 2001 ). Consequently, the Catotrichinae are rightly placed at the base of cecidomyiid classification. Not all the characters of recent Catotrichinae are necessarily in a plesiomorphous state, though, which is important to notice in phylogenetic analysis. As shown above, there are trends within the catotrichine lineage towards lengthening of the legs and wings, which is remarkable also because the reverse trends can be observed within the Cecidomyiidae-Lestremiinae for instance. In female Trichotoca fraterna the abdomen is very slender and markedly tapered towards the apex, surely an adaptation to oviposition in crevices. In Catotricha spp. this feature is less distinctive, which is another indication for intra-subfamilial morphological and ecological diversity. Male genitalic structures of Catotrichinae are also diverse, but patterns are too little understood as to have a bearing upon classification. To sum up, the Catotrichinae are not the uniform group they seemed to be thus far, and the refinement of catotrichine classification commenced here will certainly proceed.