Rocetelion humerale (Zetterstedt)

Fitzgerald, Scott J., 2019, A Revision of the Holarctic Genus Rocetelion Matile (Diptera: Keroplatidae), Zootaxa 4648 (3), pp. 568-580 : 577-579

Rocetelion humerale (Zetterstedt)

Figs. 14 , 15, 16, 17 .

Rocetelion humerale ( Zetterstedt, 1850) , p. 3445 as Ceroplatus humeralis . HT female (MZLU); Sweden.

Material examined. SLOVAKIA: centr., Polana Biosphere Reserve , Hrončecký grúň N.N.Res., 13.7.2016 (sweep- ing), J. Ševčík leg. (1 male, SFC) .

Diagnosis. Males of R. humerale are most similar to R. fenestrale and can be distinguished by the following characters: shape of the cerci more oval-shaped in R. humerale and more angular or diamond-shaped in R. fenes- trale, posterior margin of the epiproct of R. humerale truncate with a small median depression versus apically gently rounded in R. fenestrale , and the posterior edge of tergite nine more truncate in R. humerale than in R. fenestrale (compare Figs. 15–17 & 5–6 ). Furthermore, in the few specimens studied, males of R. humerale have longitudinal stripes on the mesonotum and a distinctly banded abdomen ( Fig. 14 ) while R. fenestrale has the dorsum of the me- sonotum with a large black median area (albeit the shape of fused longitudinal stripes) and an unbanded abdomen (though the base of tergites four and five have faint pale areas laterally; Fig. 2 ). No females of R. humerale were examined as part of the present study, but both males and females can also be distinguished from R. fenestrale by the disjunct distributions of these species; R. humerale in the Palearctic and R. fenestrale in the Nearctic.

Distribution. This species is widespread in northern and central Europe with records from Czech Republic, Estonia, Finland, Germany, Hungary, Latvia, Norway, Poland, Russia (Central and Northern European), Slovakia, Sweden, Switzerland, and UK ( Evenhuis 2006, Chandler 2013). According to Zaitzev (1994), it is also recorded from the Eastern Palearctic (Altai Republic in Russia).

Biology. Horsfield (2000) reared R. humerale from an unidentified polypore on a birch log in Scotland. Remarks. See under “Remarks” for R. fenestrale .

Figures

FIGURE 2. R. fenestrale, male, habitus (Alaska, USA). Scale bar = ca. 1.0 mm.

FIGURE 14. R. humerale, male habitus (Slovakia). Photo by Jan Ševčík.

FIGURES 15–17. Male terminalia of R. humerale. 15. Dorsal. Scale bar = ca. 0.5 mm. 16. Ventral. Scale bar = ca. 0.5 mm. 17. Dorsal; Tergite nine, cerci, and epiproct. Scale bar = ca. 0.25 mm. Abbreviations: cer, cerci; ep, epiproct; gc, gonocoxite; gs, gonostylus; ma, membranous area; T9, tergite 9.

FIGURES 3–6. Male terminalia of R. fasciola (3,4) and R. fenestrale (5,6). 3, 5 – dorsal view, 4, 6 – ventral view. Scale bars = ca. 0.5 mm. Abbreviations: cer, cerci; ep, epiproct; gc, gonocoxite; gs, gonostylus; ma, membranous area; T9, tergite 9.