Katatopygia, Martinsson, Svante & Kjaerandsen, Jostein, 2012

Martinsson, Svante & Kjaerandsen, Jostein, 2012, Katatopygia gen. n., a monophyletic branch segregated from Boletina (Diptera, Mycetophilidae), ZooKeys 175, pp. 37-67 : 40-42

Genus Katatopygia gen. n.

Type species.

Boletina sahlbergi Lundström, 1906: 14(type deposited in MZHF)

Diagnosis.

The genus consists of medium sized slender Gnoristinae with long abdomen where the males have a very characteristically flattened and dilated terminalia (eg. Fig. 3E). They can be recognized on a combination of the following characters: mouthparts not prolonged; scutum with setae arranged in acrostichals, dorsocentrals and laterals; laterotergite bare; wing with Sc ending in C; M-petiole as long as or longer than ta; CuA-furcation before level of M-fork, approximately level with base of Rs; abdominal sternites with median fold-line absent; male terminalia broad and dorsoventrally flattened, often rotated about 180°; gonostylus large and simple, bear ing an apical processus (except in Katatopygia neoerythropyga ); parameres fused dorsally into one caudally directed rod (with one exception, Katatopygia antoma , that has pared parameres); cerci large and without retinacula, covered with long trichia; hypoproct well developed; female terminalia with unsegmented cerci. The best characters to separate between Katatopygia and Boletina s.s. are further listed in Table 3.

Description.

Adults: Medium sized, slender with long abdomen, body length 4.5-6.5 mm (Fig. 3).

Head (Fig. 4A). Vertex with scattered setae. Ocelli three, almost in line, the median slightly smaller than laterals, lateral ocelli separated from eye by approximately 1.5 times its diameter; below the ocelli, protuberances present and well sclerotized. Eyes with shallow emargination above antennal base. Frons without setae but with small microtrichia and on lateral parts some stronger microtrichia; frontal furrow well developed and reaching apex of frontal tubercle. Antenna with 14 flagellomers; scape and pedicel with a few scattered setae and short microtrichia (Fig. 4E); flagellomeres long rectangular, densely covered with medium sized setae; apical flagellomere with a somewhat stronger terminal seta (Fig. 4D). Face with scattered setae. Mouthparts not prolonged; clypeus oval to subtriangular and well separated from face, sclerotized and bearing setae; palps with five palpomeres, the first being reduced and easily overlooked, third palpomere with sensillae on inner surface.

Thorax (Fig. 4B). Antepronotum fused with proepisternum, bearing some setae, the suture between the sclerites weak. Scutum with setae arranged in acrostichals, dorsocentrals and laterals, otherwise bare. Scutellum with one pair of bristles and scattered setae. Anepisternum, anepimeron latero- and mediotergite all bare.

Wings (Fig. 5 A–B). Wing membrane unspotted, yellow tinged with dense, irregular arranged microtrichia and no macrotrichia. Crossvein h bare; costa, R1, and R5 with both dorsal and ventral setae; M1, M2, CuA1 and CuA2 with dorsal setae; subcosta bare or with a few setae on distal part; ta, tb, M-petiole, CuA-petiole, A1 and A2 without setae; C ending in, or slightly produced beyond apex of R5; Sc ending in C before or in level with base of Rs; Sc2 present, but may be reduced; R4 absent; M-petiole between 1 and 2 times as long as ta; CuA-fork starts proximally of M-fork, approximately at the level of base of Rs; A1 ending at or slightly before CuA-fork; A2 indistinct and short.

Legs (Fig. 4C). Legs often pale with dark setation; fore and mid coxae with some setae on apical part; trochanter dark; bearing sensillae and a few small setae; femur with numerous setae and no bristles; tibia covered with irregularly arranged setae and with bristles mainly confined to ventral surface; fore tibia with anteroapical depressed area semicircular and densely covered with long microtrichia; apical tibial spur serrated and covered with microtrichia, no apical comb present; tarsus covered with macrotrichia and some stronger setae; claws with a small ventral lobe; empodium pulvilliform.

Abdomen. Pale abdominal markings, when present, situated towards the apices of the tergites. Sternite 1 with a few weak setae apically, all other segments haired; sternites with sublateral fold-lines, median fold-line absent; segment 7 and 8 reduced and retracted into segment 6.

Male terminalia (Fig. 6 A–B). Broad and dorsoventrally flattened; often rotated about 180°. Tergite IX rather small and subrectangular, in some species with a mesial sclerotized suture, scattered with setae.Cerci large, rounded to oval, without retinacula, densely covered with long microtrichia. Gonocoxites large, moderately incised ventrally with a hypandrial lobe situated in this incision; hypandrial lobe well developed and more or less branched; gonocoxite bearing scattered macro- and micotrichia, long microtrichia densely covering apical margin. Tergite X present as a weakly sclerotized, short and broad plate situated ventrally, near apex of tergite IX. Hypoproct well developed, situated ventrally to cerci and fused with tergite X, setose and resembling a second segment of cercus. Gonostylus large, unbranched except posessing a tiny apical processus which articulates to a small unsclerotized area and bears 1-2 strong setae, in some species this processus is minute or absent; apex of gonostylus covered with dense retinacula; ventrobasally surface of gonostylus with patch of placoid sensillae; inner surface of gonostylus usually fringed with small dentations. Accessory copulatory appendages joined to gonocoxite through a weakly sclerotized gonocoxal apodeme attached near apex of aedeagus. Aedeagus apically connected with parameres; in most species the parameres are fused dorsally into one caudally directed rod; aedeagus with well developed sperm sacs, to which vas deferens is attached.

Female terminalia (Fig. 7 A–F). Tergite VIII well developed, subrectangular. Sternite VIII well developed, entirely fused with gonocoxite VIII that is tapered and bearing several strong setae at apical margin. Tergite IX well developed, shorter than Tergite VIII. Gonapophysis VIII hyaline, indistinct. Gonapophysis IX ventrally divided and retracted into segment VIII, in some species projected into a pointed apex, while in other short and blunt. Tergite X very short, laterally fused with sternite X that is completely divided ventrally and projected caudally. Cerci one-segmented, ovate.

Larvae unknown.

Notes on biology.

The Nordic species are most abundant in boreal Taiga and subarctic environments, and are possibly strictly boreal-montane. The adults, at least of Katatopygia sahlbergi , seem to be attracted by light, which could suggest nocturnal activity. Larval habitats are unknown for all species in the genus.

Distribution.

A mainly Holarctic genus with the exception of Katatopygia laticauda (Saigusa, 1968), comb. n. described from Taiwan in the Oriental Region ( Saigusa 1968). The greatest diversity is found in Western North America and in the Eastern Palaearctic with four species in each of the regions (Table 1).

Etymology.

Katatopygia is derived from the Greek words katatonis, meaning "broader than high", pygo-, meaning “rump” or “buttock” and the suffix -ia denoting pertaining to. The name refers to the characteristic broad and dorsoventrally flattened terminalia shared by all males in the genus. The name is a noun and is feminine.

The species of Katatopygia