Cooka incisa (Cook, 1956)

Haenni, Jean-Paul & Paltrinieri, Lucia Pollini, 2021, First report of Cooka incisa (Beekey, 1937) from Europe (Diptera, Scatopsidae), Alpine Entomology 5, pp. 1-4 : 1

Cooka incisa (Cook, 1956) Figs 1-4 , 5

Rhexoza incisa Cook, 1956: Ann. Ent. Soc. Am. 49: 6, figs 2A, 2G, 3B.

Rhexoza incisa Cook in Stone & al., 1965: Cat. Dipt. N. Amer.: 240.

Rhexoza incisa Cook, 1975: Pan-Pac. Entomol. 51: 66, figs 13, 24-25.

Rhexoza incisa Cook, 1981: Manual of Nearctic Diptera 1: 315, figs 20-22.

Cooka incisa (Cook, 1956): Amorim 2007: Zootaxa 1640: 48.

Material studied

(12♂♂, 4♀♀). Switzerland, TI: Bolle di Magadino, [Gordola, Reviscài], 199 m, 710.121/114.037 [46°10'07.685"N, 8°51'52.248"E], forest, mid June-end July 2000, 1♂; same locality but mid June-end July 2001, 3♂♂ 1♀; same locality but mid June-end July 2004, 2♂♂; same locality but mid June-end July 2005, 2♂♂, all P. Duelli leg., CGB, MHNN; Lugano, 24.VI-5.VIII.2006,1♂, Th. Sattler leg., MHNN; Losone, Arcegno, Collina di Maia, 420 m, 701.151/113.376 [46°09'51.337"N, 8°44'53.687"E], ARC1, 21-28.VII.2015, birra bianca, 2♀♀; same, but 7-18.VIII.2015, 1♂ 1♀; same, but 411 m, 701.013/113.741 [46°10'03.240"N, 8°44'47.535"E], ARC2, 28.VII-7.VIII.2015, vino, gialla, 1♀; same, but, 366 m, 701.307/113.196 [46°09'45.434"N, 8°45'00.812"E], ARC3, 7-26.VII.2016, birra bianca, 1♂, all L. Pollini & M. Abderhalden leg., MSNL.

Diagnosis.

Body, elongate (Fig. 1 ), dull in general appearance, except for contrasting, shining tergite 7 and basally sub-shining sternite 7 in male. Wing venation (Fig. 2 ) very similar to that of Rhexoza species and of the cosmopolitan Coboldia fuscipes . Tergite 7 (Fig. 3 ) with median posterior projection broad, sternite 7 deeply incised medially, genital capsule (Fig. 3 ) with elongate, pointed, posteriorly directed lateral projections, aedeagus short. Female (Fig. 4 ) with tergite 8 deeply incised medially, sternite 8 broadly divided in two basally broad, apically pointed lateral lobes.

The Swiss material perfectly agrees with the description and figures of North American specimens of this species, especially regarding the very characteristic shape of the male genital capsule (Cook, 1981: fig. 20.22, and present paper, Fig. 3 ). Cooka incisa will run to Rhexoza in the key to the Palaearctic genera of Scatopsidae ( Haenni 1997), but can be differentiated from the four known European species of Rhexoza by the features given in the diagnosis. Furthermore, the pregenital segment of C. incisa is shiny, strongly contrasting with the other abdominal tergites in the male, which are dull (pregenital segment only partly shining in female). All tergites are dull in Rhexoza .

Distribution.

Cooka incisa was described by Cook (1956) (as Rhexoza incisa ) from the Great Lakes region (USA: Iowa, Illinois, Minnesota; Canada: SE Ontario). It is recorded here for the first time from Europe and the Palaearctic region as a whole. In Europe it is presently known only from the Swiss canton of Ticino in the localities cited above.

Biology.

"The larvae of this species have been collected from beneath the bark of dead American elm [ Ulmus americana ], box elder [ Acer negundo ] and cottonwood [ Populus spp.] trees" in the USA ( Cook 1956: 8), where this species is bound to wet areas. One of the Swiss localities, namely Bolle di Magadino, is a riverine forest which presents similar characteristics (main tree species are Alnus glutinosa , Fraxinus excelsior , Quercus robur , Ulmus spp., Salix alba and Populus spp., while Acer negundo is also present in the region). In Arcegno, on the other hand, C. incisa was caught in a forest consisting of chestnut ( Castanea sativa ) together with oak ( Quercus petraea , Q. pubescens , Q. robur and Q. rubra ) ["castagneto con querce"].

Figures

Figure 5. Cooka incisa (Cook), male, antepronotum and anterior spiracular sclerite (iap: indentation of antepronotum).

Figures 1 - 4. Cooka incisa (Cook): 1. Habitus, male, lateral view. 2. Wing, male. 3. Tip of abdomen and genital capsule, male, ventral view; inset a. Genital capsule, dorsal view (true ventral, as genitalia rotated through 180 °). 4. Tip of abdomen, female, lateral view.