THE TRUE IDENTITY OF COPELAND'S AQUATIC SCUTTLE FLY (DIPTERA: PHORIDAE) FROM INDIANA AND RECOGNITION OF A SIBLING SPECIES FROM TEXAS

Abstract

Among the insects reported by Copeland (1989) breeding in the waters retained by treeholes in Indiana was a scuttle fly identified by W. H. Robinson as Megaselia scalaris (Loew). It is here reported that in fact this fly, along with fresh material from Illinois and Missouri, is M. imitatrix Borgmeier, whose type series was from Puerto Rico. An aquatic species reported from Texas is recognized as a sibling species of M. imitatrix and is named M. hansonix Disney, sp. nov. A single female from Brazil represents a third species of this complex, thus raising doubts about the identity of specimens from Brazil attributed to M. imitatrix by Benton and Claugher (2000).

Figs. 1–2

Megaselia hansonix male hypopygium. 1, Left face. 2, Right face with only base of anal tube included. Scale bar = 0.1 mm.

Figs. 3–4

Megaselia hansonix female, details of abdomen. 3, Tergites 5–7. 4, Furca and associated vaginal sclerite. Scale bars = 0.1 mm.

Figs. 5–7

Megaselia hansonix. 5, Male, left notopleuron and parts of adjacent regions (P = propleuron, H = humeral bristle, N = notopleuron, I = base of intra-alar bristle). 6–7, Larva stage III. 6, Left face of mandibles and cephalopharyngeal skeleton. 7, Left mandible. Scale bars = 0.1 mm.

Figs. 8–9

Megaselia imitatrix male hypopygium. 8, Left face. 9, Right face with only base of anal tube included. Scale bar = 0.1 mm.

Figs. 10–13

10–12, Megaselia imitatrix female, details of abdomen. 10, Tergites 5–7. 11, Dufour's crop mechanism. 12, Furca and associated vaginal sclerite. 13, M. scalaris female, Dufour's crop mechanism. Scale bars = 0.1 mm.

Figs. 14–15

Megaselia females, left lobes at rear of abdominal sternum 8. 14, M. hansonix. 15, M. imitatrix. Scale bar = 0.1 mm.

Figs. 16–17

Megaselia scalaris. 16, Left face of male hypopygium. 17, Female abdominal tergites, rear of T4–T7. Scale bars = 0.1 mm.

Figs. 18–19

Megaselia scalaris. 18, Female, furca. 19, Left face of mesopleuron and parts of adjacent regions (S = spiracle , N = notopleuron, P = post-propleural ridge, M = mid-mesopleural ridge). Scale bars = 0.1 mm.

Figs. 20–22

Megaselia scalaris pre-adult stages. 20, Larval stage III, left face of mandibles and cephalopharyngeal skeleton. 21, Left mandible of larva. 22, Median tooth of larva. 23, Dorsal view of egg. Scale bars = 0.1 mm.