Genus Cirrula Cresson

Cirrula Cresson 1915: 70 [type species: Cirrula gigantea Cresson, by monotypy].— Sturtevant and Wheeler 1954: 162 –163 [review].— Wirth 1965: 753 [Neotropical catalog].— Mathis and Simpson 1981: 8 –29 [revision of North American species, natural history].— Mathis and Zatwarnicki 1995: 236 –237 [world catalog].

Pogonephydra Hendel 1917: 42 [type species: Pogonephydra chalybea Hendel (= C. gigantea), by monotypy] [Synonymy by Hendel 1931: 10].

Hydropyrus Cresson 1934: 216 [type species: Ephydra hians Say, by original

designation and monotypy].— Sturtevant and Wheeler 1954: 171 [review; as subgenus of Ephydra].— Wirth 1965: 753 [Neotropical catalog]; 1971: 374–376 [review, Figs. of male terminalia; as subgenus of Ephydra].— Mathis and Zatwarnicki 1995: 236 [synonymy].

Diagnosis. Cirrula is distinguished from other genera of Ephydrini by the following characters: Moderately large to large shore flies, body length 4.83–8.52 mm.

Head: Cruciate, interfrontal setae 1–2 pairs, size generally subequal to fronto-orbital setae (weakly developed in C. gigantea, especially females); lateroclinate, fronto-orbital setae either 2 or 3–4 pairs, slightly divergent, if 2, then dorsocentral setae (1+4), if 3–4, then dorsocentral setae (2+4); antenna simple, lacking secondary seta inserted on lateral surface just below arista; arista bare to macropubescent; face uniformly setose with marginal setae larger, declinate, one species with patches of long setae above middle height of face on anterior surface of interfoveal hump.

Thorax: Prescutellar, acrostichal setae variable; dorsocentral setae 5–6 pairs (5 (1+4) in specimens with 2 fronto-orbital setae, 6 (2+4) in specimens with 3–4 fronto-orbital setae), well developed in Neotropical species; supra-alar seta present; presutural supra-alar seta variable; intrapostalar seta well developed. Legs sexually dimorphic; hindtibia lacking apical, long seta.

Abdomen: Male terminalia symmetrical; surstyli complex, situated at ventral apex of epandrium, covering other internal structures in repose, fused medially; phallapodeme more or less C-shaped with a dorsal lobe extended far into epandrial cavity; aedeagus generally simple except in males of C. austrina, where trilobate process arises at anterior base of aedeagus. Female ventral receptacle with large operculum, generally as long as wide; extended process J-shaped, length about as long as operculum; conformation of receptacle in females of D. spinosa exceptional, operculum trapezoidal and much smaller, extended process three times as long as operculum length.

Larva: Prolegs distinct; segment 3 of third-instar larvae with distinctive transverse band on venter.

Distribution. New World. Primarily temperate Nearctic Region but extending south into the northern Neotropical Region (Belize (Stann Creek District)).