Coelophthinia Edwards, 1941

Kjaerandsen, Jostein, Kerr, Peter H., Lindemann, Jon Peder & Kurina, Olavi, 2023, When details matter: Integrative revision of Holarctic Coelophthinia Edwards (Diptera, Mycetophilidae), including mapping of its mitogenome, leads to the description of four new pseudocryptic species, Biodiversity Data Journal 11, pp. 98741-98741 : 98741

Coelophthinia Edwards, 1941

Coelophthinia Coelophthinia thoracica (Winnertz, 1864)

Description

A Gnoristinae genus with slender and medium-sized (2.8-4.3, 3.8 mm) species (Figs 1 , 2 a). Coloration quite uniformly brown, darker on head and preterminal, abdominal segments, three brown thoracic stripes distinctly contrasted against yellow humeral areas (Fig. 2 b), abdominal tergites II-IV sometimes apically paler, legs and terminalia mostly yellow. Head (Fig. 2 b, c) round, eyes slightly kidney-shaped, but without tendency of dorsal eye-bridge expansion, inter-ommatidia pubescent. Antenna moderately slender, with 16 segments, medium-sized, semi-globular scape and pedicel and flagellar segments 3-4 times as long as wide. Frons with greatly reduced, incomplete frontal furrow and relatively broad frontal tubercle (Fig. 2 c). Mouthparts average, with five, gradually longer palpal segments, no clear sensory pit discernible in third segment (without slide mounting). Clypeus horseshoe-shaped, with scattered, long setae. Three ocelli in a near straight line, middle ocellus half the size of the lateral ocellus, lateral ocellus less than its diameter from eye. Thorax (Fig. 2 a, b, e). Antepronotum with pair of medium-sized antepronotal setae. Mesonotum scattered with short setae, only moderately defined into rows, but rich in larger setae laterally. Mesopleurites without setae, mediotergite with row of strong setae basally. Wings (Fig. 2 d) unpatterned hyaline with a slight brown tinge, with wing interference colours (Fig. 1 , see Shevtsova et al. (2011)) in first order Newton colour scale, indicating very thin (less than 200 nanometres thickness) and even membrane beyond the wing base, wing membrane with irregularly arranged microtrichia. Costa produced slightly beyond to 1/4 between R4+5 and M1, subcosta long, ending in C proximal to crossvein Rs, midway with crossvein sc-r. Radial sector with oblique crossvein Rs, without R2+3. Anterior fork long, with short stem subequal to r-m. Posterior fork short, widely divergent. Radial sector and both forks with setae on dorsal surface beyond base. Legs (Fig. 2 a, e) with irregularly arranged setulae. Fore tarsus subequal in length to fore tibia, tarsal ratios can be extracted from Fig. 2 e. A distinct sense organ present dorsally on the basal part of mid-tibia (Fig. 2 e, f), of variable length between species.

Male terminalia (Fig. 3) apparently always positioned with a 180 degrees torsion in relation to abdomen (Fig. 1 ). Tergite 9 (Fig. 3 a, c, d) short, wide rectangular, strongly setose, medially slightly constricted, with basal margin concave. Tergite 10 unusually well developed (Fig. 3 c, d), with medial, densely setose, dorsally protrusive lobe and lateral extension armed with three strong setae. Hypoproct and cerci (Fig. 3 a, c) forming elongate, basally fused lobes arising from underside of tergite 9, apically setose. Gonocoxites separated ventrally (Fig. 3 b), strongly setose, except bare posterolateral lobes, which have one subapical, internal, medially directed small and stout seta (Fig. 3 e). Setae on dorsal side of gonocoxite similar to those on ventral side. Posterolateral lobe of gonocoxite situated midway between dorsal and ventral edges (Fig. 3 a, b, e), narrow, shape varies between species, always with one stiff, short seta apicointernally (Fig. 3 e). Ventral medial margin of gonocoxite with a narrow, long, spathulate lobe (Fig. 3 b, e), whose shape varies between species. Aedeagal guide (Fig. 3 c) forming a knob with 3-5 medially directed setae deviating from other setae anteriorly on the base of the gonocoxal lobe. Gonostylus (Fig. 3 b, e, f) small, internal with two branches, dorsal branch semicircular with normal setae, ventral branch bifurcated into two lobes (lb 1 & lb 2 in Fig. 3 f), with truncated, blunt setae. Aedeagal apparatus (Fig. 3 b, c) large, elongated, with strong, downcurved tip, basally attached to gonocoxite via strip like gonocoxal apodemes (Fig. 3 c).

Female terminalia (Fig. 4) rather truncated, with short tergites 8 and 9. Tergite 9 wide, subrectangular, with some setae extending towards epiproct dorsally. Cercus one-segmented, large ovate, evenly covered with setae. Hypoproct/Tergite 10 forming narrow process along underside of cerci, with some setae. Gonocoxite 8 moderately split ventrally, with free, sclerotised, pointed lamellae. Sternite 9 small, retracted within terminalia.

Diagnosis

Males of the genus Coelophthinia are easily distinguished from all other Gnoristinae genera by the characteristic shape of their torsioned terminalia (Figs 1 , 3), especially the open gonocoxite with long apicolateral and medioventral projections in combination with a small, internal gonostylus armed with a fan of blunt setae. The protrusive lobe of tergite 10 in the males (Fig. 3 c, d) is a further unique characteristic for the genus. Both sexes can be distinguished from other Gnoristinae genera also by the wing venation (Fig. 2 d) where the wide posterior fork is similar only to that of genus Coelosia Winnertz, 1864. From Coelosia , Coelophthinia differs in having crossvein sc-r present and in having a row of setae on the basal part of the mediotergite.

Figures

Figure 1. Live photo of the type species for the genus, a Coelophthinia thoracica (Winnertz, 1864) male resting on a window in a barn in western Norway. The photographed specimen was subsequently collected, DNA barcoded and assigned to Barcode Index Number (BIN) BOLD: ACJ 0721 (Specimen ID TSZD-JKJ- 111214). The mid-tibial organ is visible and marked with a red arrow. The 180 deg. torsion of the male terminalia is also visible.