Wheeleriola, Jaschhof & Jaschhof, 2020

Jaschhof, Mathias & Jaschhof, Catrin, 2020, Wheeleriola perplexa gen. et sp. nov., the first member of Catotrichinae (Diptera Cecidomyiidae) found in New Zealand, Zootaxa 4852 (5), pp. 565-570 : 566-567

Wheeleriola gen. nov.

Type species: Wheeleriola perplexa sp. nov., described below. Monotypic.

Diagnosis. Among cecidomyiids with long first tarsomeres, i.e. Catotrichinae , Lestremiinae and Micromyinae , Wheeleriola is unique for its wing venation, which is characterized by Rs being obliquely aligned (i.e. almost parallel to M 1+2), Rs and r-m perpendicular to each other, M 1+2 single-branched and apically faded, and M 4 absent ( Fig. 1 ). [A superficially similar pattern is found in Diallactia Gagné ( Jaschhof & Jaschhof 2013 : fig. 25A), a genus of the subfamily Winnertziinae , where the first tarsomeres are shortened.] In Catotrichinae other than Wheeleriola , M 1+2 is furcate, both branches (M 1 and M 2) being consistently strong up to the edge of wing, and M 4 is present as an equally strong vein whose base enters the transverse vein made of bM 4 + bm-m ( Jaschhof & Fitzgerald 2016: fig. 8). The new genus is based on male characters, females and larvae being unknown.

Other male characters. Head. Ocelli lacking. Number of flagellomeres unknown, with maximally two retained on one side. Necks of flagellomeres long, without sensilla; nodes subcylindrical, with microtrichia (only basally), setae (only basally), sensory hairs arising from small, hooded alveoli (scattered on distal half with appreciable concentration near midlength), and hair-shaped translucent sensilla (irregularly scattered on distal two thirds) ( Fig. 2 ). Palpus with 4 setae-bearing segments ( Fig. 3 ). Thorax. As described for Trichotoca fraterna (Jaschhof) except that setae are confined to scutum and scutellum ( Jaschhof & Jaschhof 2008 : fig. 3A). Wing ( Fig. 1 ) long and narrow, without anal lobe. Membrane fully setose. C without break near wing apex. Sc and CuP present; h and sc-r absent. A fold present above CuA should not be mistaken for a vein. Legs. Setae fairly uniform, short; no scales. [Legs of the holotype broken off behind first tarsomeres.] Abdomen. Sclerites entire, with sparse, large setae; first sternite and pleural membrane non-setose. Genitalia more complex than that found in the Australian Trichotoca Jaschhof & Jaschhof , including bilobed gonostylus and process-bearing tegmen ( Figs 5–6 ).

Discussion of characters and classification. In spite of its strongly reduced medial veins we regard Wheeleriola as a member of the Catotrichinae , for most of its morphology supports no other conclusion. The peculiar position of Rs and r-m, as well as the lack of the costal break ( Fig. 1 ) are conditions typical of the Catotrichinae but rarely found outside that subfamily, as are the flagellomeres ( Fig. 2 ) which lack the strictly regular arrangement of sensory hairs into crenulate whorls as is characteristic of Lestremiinae and Micromyinae ( Jaschhof & Jaschhof 2009 : fig. 10A–B). The flagellomeral vestiture of Wheeleriola ( Fig. 2 ) differs from that of all other Catotrichinae ( Jaschhof & Jaschhof 2008 : fig. 1A) in two details: the sensory hairs are not entirely randomly distributed but tend to form an irregular girdle in the middle of the node, and the thickened, apical section of the neck bears no hair-shaped sensilla (marked by an x in Fig. 2 ). The lack of ocelli is an unusual condition in Catotrichinae , although also missing in the Nearctic Trichoceromyia Jaschhof & Fitzgerald. The genitalic structures of Wheeleriola are as complex as those of Catotricha Edwards , a genus confined to the Northern Hemisphere, although the similarities are superficial and in our opinion not indicative of a sister-group relationship. The overall picture of Wheeleriola is that of a morphologically advanced subgroup within the otherwise predominantly plesiomorphous Catotrichinae . As discussed at the end of this paper, there are reasons to regard Wheeleriola as an intermediate link between Catotrichinae and Micromyinae , although it would be premature to classify this genus in a subfamily of its own. Its classification in the subfamily Micromyinae , close to the tribes Catochini and Strobliellini , would be a conceivable alternative, but only by employing a less parsimonious argumentation.

Etymology. This genus is named after the North American entomologist and taxonomist Quentin D. Wheeler. In so doing we express our deference to Dr Wheeler’s resolute espousal of taxonomy being a modern, independent and hypothesis-driven discipline of biological science (e.g. Wheeler 2004, 2020). The gender of the generic name is feminine.

Figures

FIGURES 1–6. Male morphology of Wheeleriola perplexa, holotype. 1: Wing, dorsal. 2: Second flagellomere, lateral (x = area with sensilla in other Catotrichinae). 3: Palpus, lateral. 4: Genitalia, ventral. 5: Gonostylus, ventral. 6: Tegmen and aedeagal apodeme, ventral. Scale for 1, 0.5 mm; for 2–6, 0.05 mm.