Cirrula austrina (Coquillett)

Mathis, Wayne N. & Marinoni, Luciane, 2016, Revision of Ephydrini Zetterstedt (Diptera: Ephydridae) from the Americas south of the United States, Zootaxa 4116 (1), pp. 1-110 : 76-80

24. Cirrula austrina (Coquillett)

Figs. 104–110 , Map 24

Ephydra austrina Coquillett 1900: 36 .— Aldrich 1905: 629 [Nearctic catalog].

Caenia [sic] virida Hine 1904: 65 [description].— Cresson 1916: 152 [synonymy].

Ephydra viridis .— Aldrich 1912: 101.

Dimecoenia austrina .— Cresson 1916: 152.— Sturtevant and Wheeler 1954: 166 [review].— Wirth and Stone 1956: 472 [review].— Wirth 1965: 755 [Nearctic catalog].— Steyskal 1970: 463 [review, Figs. of male and female terminalia].

Cirrula austrina .— Mathis and Simpson 1981: 9 –21 [revision, generic combination, Figs. of adult and immatures, natural history].— Mathis and Zatwarnicki 1995: 236 [world catalog].— Mathis 1997: 64 –65 [review, Belize].

Diagnosis. This species is related and similar to C. gigantea Cresson but is distinguished by the following combination of characters: Moderately large to large shore flies, body length 4.80–6.80 mm; mostly dull, olivaceous to grayish brown, with subshiny to shiny areas on dorsum. Head: Lateroclinate fronto-orbital setae 2, well developed; cruciate interfrontal setae 1, long, over 2/3 length of arista, overlapping apically; parafrons brownish to brownish gray, microtomentose but not velvety; aristal rays slightly longer than aristal width at base; interfoveal hump distinctly projecting anteriorly; dorsum of face lacking patche(s) of long setae. Thorax: Dorsocentral setae 5 (1+4) well developed, subequal; presutural seta well developed, equal to or longer than anterior notopleural seta; lacking distinct prescutellar, acrostichal setae and presutural supra-alar setae. Hindfemur of male enlarged, swollen; hindtarsi of male shortened and bearing tufts of long hairs; legs generally dark; tarsi of foreleg normal, cylindrical, similar to those of midleg. Abdomen: Hypandrium evident as a well-sclerotized process; setae of epandrium around cercal cavity similar to other epandrial setae.

Head ( Figs. 104–105 ): Head ratio 0.58; frontal ratio 0.51; subquadrate mesofrons shiny with metallic olivaceous to greenish blue luster; cruciate interfrontal setae 1 pair, remainder of mesofrons with small inconspicuous setae; ocellar triangle and parafrons mostly concolorous, brownish gray, the latter becoming slightly darker anteriorly; ocelli in isosceles triangle, distance between posterior pair much less than between either posterior ocellus and medial ocellus; medial ocellus marking posterior extension of shallow depression; lateroclinate fronto-orbital setae 2 pairs; postocellar setae only moderately well developed; postocular setae more or the uniform in size. Antenna more or less unicolorous, brownish gray to charcoal gray; arista longer than combined length of 1st 3 antennal segments gradually tapered to style-like apex; subpectinate dorsally just apicad of midpoint to near base. Facial ratio 0.73; interfoveal hump prominent, dorsum shiny, nearly concolorous with shiny mesofrons; antennal groove deeply impressed, more or less concolorous with remainder of face but less microtomentose and tending to be somewhat subshiny with very pale greenish blue luster; face olivaceous to argentous, darker dorsally; marginal facial setae larger, extended from interfoveal hump to posteroventral corner of face more or less uniformly, gently curved posteriorly; oral margin weakly emarginate toward midpoint. Eye ratio 1.2; gena-to-eye ratio 0.29; gena only moderately wide, mostly bare except for small setae paralleling parafacial suture, mostly concolorous with face, becoming darker and setulose posteriorly.

Thorax ( Fig. 106 ): Mesonotum generally subshiny, slightly darker and shinier posteriorly, with linear, microtomentose vittae between shiny ones, particularly evident anteriorly, color varying from grayish blue to metallic olivaceous green; acrostichal setae unseriated; dorsocentral setae 5. Pleural areas paler, more microtomentose than mesonotum, becoming paler, grayer toward venter. Legs generally dark colored, dull, microtomentose, mostly unicolorous, apices generally tawny; legs of males differing as follows ( Fig. 107 ): hindfemur enlarged, swollen, particularly basal half; hindtibia with several long hairs on ventral surface near apex; hindtarsomeres generally shorter, slightly more swollen, bearing tufts if long on ventral surfaces, more pronounced on basal segments. Wing length averaging 4.76 mm; generally hyaline or very slightly infumate, grayish brown; costal vein ratio 0.19; M vein ratio 1.1; wing length-to-width ratio 0.40.

Abdomen: Generally microtomentose, grayish blue to grayish brown, tergites darker anteriorly and along median, becoming more grayish blue toward posterior and lateral margins. Tergite 5 of male slightly longer than tergite 4, as wide as long. Male terminalia as follows ( Figs. 109–110 ): epandrium more or less parallel sided in posterior view, somewhat flattened in profile, with anteroventral margin distinctly angulate; surstylus simple, long, slender process with apex slightly recurved; gonite almost as wide as long, narrowed apically to curved point; phallapodeme long, pointed ventrally, dorsal portion broad, curved posteriorly; aedeagus short, posteroventral corner acutely pointed; hypandrium with long anterior process, anterior portion broadly bifurcate and folded back on itself. Female ventral receptacle ( Fig. 108 ) with operculum very large, as high as wide; extended process with small curved process on medial margin.

MAP 24. Distribution map for Cirrula austrina (Coquillett) .

Type material. The lectotype male of Ephydra austrina (designated by Mathis and Simpson 1981: 9) is labeled “Fl[orid]a./Collection, C. V. Riley/ Type No 4299 USNM [red].” The lectotype is pinned directly, is in good condition (some setae of the head and thorax are missing, mesonotum cracked where pinned), and is deposited in the USNM (4299).

Type locality. United States. Florida. Brevard: Georgiana (28°17'N, 80°40.5'W).

The lectotype female of Caenia [sic] virida (designated by Mathis and Simpson 1981: 9) is labeled “Brownsville, Texas, apr 12 may 20 / TYPE [red].” The lectotype is deposited in the Ohio State University (Columbus); apparently it is the only extant specimen of the original syntype series. Hine's original description also indicated that Charles Dury collected the syntype series in 1903.

Additional specimens examined. ANGUILLA. Sombrero Island (18°35.2'N, 63°25.6'W; freshwater pool), 9– 13 Nov 1999, M. A. Ivie, J. B. Runyon (1♂, 1♀; USNM).

BELIZE. Stann Creek District: Carrie Bow Cay (16°47'S, 88°04'W), Mar 1988, W. N. Mathis (1♂, 2♀; USNM); Stewart Cay (16°46'S, 88°09'W), Mar 1988, W. N. Mathis (1♀; USNM); Twin Cays (16°49.8'S, 88°06.1'W; Aanderaa Flats, West Pond), Mar 1988, W. N. Mathis (2♂, 19♀; USNM).

CUBA. Hanana: Puerto Escondido (22°57'S, 82°24'W), 26 Apr 1983, W. N. Mathis (1♂; USNM).

CAYMAN ISLANDS. Grand Cayman. Bodden Town (1.6 km E; 19°17.5'N, 81°13.3'W; Meagre Bay Pond), 29 Apr 1993, W. N. Mathis (11♂, 9♀; USNM); Hutland (1 km W; 19°21'N, 81°13.3'W), 29 Apr 1994, W. N. Mathis (1♀; USNM); Spotts (19°16.5'N, 81°19.1'W), 25 Apr 1994, W. N. Mathis (4♂, 8♀; USNM); North Sound, Bobby Cay (19°18'N, 81°18'W; light trap), 6 May 1938, C. B. Lewis, G. H. Thompson (2♂, 1♀; BMNH). Little Cayman. South Town (S coast; 19°40'N, 80°05.1'W), 30 May 1938, C. B. Lewis, G. H. Thompson (3♂, 7♀; BMNH).

MEXICO. Nayarit: Isabel Island (21°51'N, 105°53'W), 24 May 1925, H. H. Keifer (7♂; USNM). Sonora: San Carlos Bay (27°56'N, 111°03'W), 8 Jul 1921, E. P. Van Duzee (1♀; USNM); San Jose Beach (40 mi SE Obregon; 27°28'N, 109°56'W), 18 May 1961, H. Howden, J. Martin (3♀; CNC).

Distribution (Map 24): Nearctic: Bermuda, United States (California, Florida, Maryland, Texas Virginia). Neotropical: Belize, Mexico (Nayarit, Sonora), West Indies ( Cuba, Cayman Islands, Sombrero).

Natural history. Mathis and Simpson (1981) published a detailed report on the natural history of this species, and their study should be consulted for more complete details. They successfully reared specimens from several localities along the coast of Virginia and noted that immatures and adults reached their highest densities where the habitat was partially dried, leaving algal mats on firm ground. Adults were collected commonly by sweeping over these mats.

Unlike the larvae of Dimecoenia spinosa , those of C. austrina have eight pairs of well-developed prolegs and the third-instar larva also has a dark transverse strap at the anteroventral margin of segment three.

Figures

FIGURES 104 – 107. Cirrula austrina (Coquillett). (104) head, lateral view; (105) same, anterior view; (106) mesonotum, dorsal view; (107) hindleg of male, lateral view and dorsal view of tarsi (from Mathis and Simpson 1981).

FIGURES 108 – 110. Structures of male and female terminalia of Cirrula austrina (Coquillett). (108) female ventral receptacle, lateral view; (109) male terminalia, lateral view; (110) ventral margin of epandrium and surstyli, posterior view (from Mathis and Simpson 1981).