Micromorphus caudatus (Aldrich) Bickel, 2022

Bickel, Daniel J., 2022, Notes on the genus Micromorphus Mik (Diptera: Dolichopodidae) and the uncertain identity of its type species, M. albipes (Zetterstedt), Zootaxa 5125 (4), pp. 437-444 : 439-442

Micromorphus caudatus (Aldrich) , new status

( Figs 1a–b ; 2a–c )

Achalcus caudatus Aldrich, 1902: 93 .

Micromorphus panamensis Van Duzee, 1931: 180 , syn. nov.

Micromorphus albipes (Zetterstedt), 1843: 454 ( Hydrophorus ), authors, nec. Zetterstedt.

Type material. Achalcus caudatus Aldrich was described from males and females collected on Grenada, West Indies ( USNM, examined). Robinson (1967) referred the species to Micromorphus , and later ( Robinson 1975) placed the species in synonymy with M. albipes (Zetterstedt) . Van Duzee described Micromorphus panamensis based on a single male from the Panama Canal Zone ( AMNH, examined), and Robinson (1967) also placed that species in synonymy with M. albipes .

Additional material. BELIZE: ♂, Cayo, 19.i.1991, S. Marshall ( DEBU) . COSTA RICA: Alajuela: 6 ♂, 4 ♀, 20 km S Upala , 8.xi.1990, 20.xi.1990, 10–13.ix.1990, 1–10.iv.1991, R. Hanson ( LACM) . Cartago: 6 ♂, 5 ♀, Turrialba, Tres Equis, P.N. Barbilla : Sendero Las Quebradas, 9.974291 -83.44966, 370 m, 15.x.2002; 9.9742917 -83.4496636, 200–300 m, 25.xi.2000; E. Rojas. Guanacaste: 4 ♂, 5 ♀, SE Rio Naranjo , iii, vii–ix.1991, R. Hanson ( LACM) ; 10 ♂, 8 ♀, 14 km S Cañas , i-iii, viii, x, xi, xii.1990, R. Hanson ( LACM) ; 2 ♂, 3 ♀, La Tabraga, SW Cañas , ii–iii.1990, R. Hanson ( LACM) ; 3 ♂, 4 ♀, P.N. Santa Rosa, Playa Naranjo, mangroves, 10.781949 -85.667386, 0–5 m, 11–12.xi.1995, yellow pan trap, D. Bickel ( AMS) ; 3 ♂, P.N. Santa Rosa, Rio Poza Salada , 12.xi.1995, yellow pans, D. Bickel ( AMS) ; 27 ♂, 30 ♀, Nicoya, Estro Jabilla , 8–12.xii.2002, mangroves, 5 m, Malaise trap, Y. Cardenas ( AMS) . Heredia: 2 ♂, Z.P. La Selva, 27–30.i.1989, D. Grimaldi ( AMNH) . Limon: 2 ♂, ♀, 4 km NE of Bribri , 50 m, 16.ii.1999, S. Marshall ( DEBU) . Puntarenas: 2 ♂, ♀, P.N. Corcovado, Est. Sirena , 0–100 m, 6–12.iv.1995 ( IN- BIO) ; 2 ♂, P.N. Corcovado, Est. Quebrada Ceniza. 200 m, 14.iii–5.iv.2003, K. Caballero ( INBIO) ; 2 ♂, 2 ♀, Golfito Jiménez, P.N. Corcovado, Est Sirena , Playa Sirena, 8.4801714 -83.5912892, 1–100 m, 6–12.iv.1995, A. Picado ; 3 ♂ ♀, P.N. Corcovado, Est. Sirena, La Leona, Cerro Puma , -83.5912892, 100–300 m, 6.ix–6.x-2003, Malaise trap, K. Cabillero ; ♂, Rio Termo , 90 m, 13.v.1995, M. Zumbado ( INBIO) . San José: 5 ♂, 7 ♀, Escazus , various dates, i–vii.1998, R. Hanson, ( LACM) ; 3 ♂, Pedregoso , no date ( USNM) ; ♂, San José ‚ vii ( USNM) ; San José ‚ 1100–1200 m, vii.1980 ( AMNH) ; 2 ♂, 3 ♀, Zurqui de Moravia , 1600 m, v.1996, S. Marshall ( DEBU) . San Mateo: 3 ♂, 2 ♀, Higuito , no date, F. Schild ( USNM) . DOMINICA: See records in Robinson, 1975 ( USNM) . GUATEMALA: 3 ♂, Guatemala City, 5.i.1979, G.E. Bohart ( LACM) . MONTSERRAT: See records in Runyon, 2020 . PANAMA: 5 ♂, 3 ♀, Canal Zone , iv.1923, x.1925, R. C. Shannon ( USNM) . SAINT VINCENT & GRENADINES: 2 ♂, 3 ♀, Leeward I., 1907, H.H. Smith ( USNM) . TRINIDAD & TOBAGO: Trinidad : 3 ♂, Charlottesville , 19.i.1981, G.E. Bohart ; ♂, Tunapuna-Piarco. Asa Wright Nature Centre , 19.i.1981, G.E. Bohart ( LACM) .

Redescription. Male. Length: 1.4 mm; wing: 1.3 x 0.5 mm ( Fig. 2a ).

Head. Head ovate, higher than wide; dorsal postcranium dark brown and flattened; frons and face dark brown with grey pruinosity; row of short brown postocular setae present, with two dorsalmost setae longer; pair of short converging postvertical setae posteriad of ocellar triangle; strong vertical seta and pair of strong diverging ocellar setae present; frons narrowing ventrally; face as wide as base of antennae; eye facets uniform; palp brown with apical seta; proboscis brownish; antenna dark brown; scape and pedicel subequal in length, with only short brownish vestiture; postpedicel short, triangular and apically pointed; arista-like stylus dorsal in slight depression, and slightly longer than head height..

Thorax. Mostly dark brown, with grey pruinosity on pleura and on posterior mesonotal slope; scutellum with brown base and yellowish margin but sometimes obscured; posterior mesonotum distinctly flattened; setae brown; ac absent; 5 strong dc present, 1 pa, 2 sa, 1 sr, 2 npl, 1 hm, 1 pm present; median scutellar setae strong, laterals absent; lower proepisternum with whitish seta.

Legs. CI yellow, CII and CIII brown basally but yellow distally; trochanters and legs mostly yellow, but femora II and III slightly infuscated; CI and CII with short brownish anterior setae; CIII with dark brown lateral seta near ½; legs with short brown vestiture; I: 1.5; 1.6; 0.8/ 0.4/ 0.3/ 0.2/ 0.2; leg I bare of major setae; II: 2.0; 2.0; 1.0/ 0.6/ 0.4/ 0.2/ 0.2; FII with strong anterior preapical seta; TII with strong ad seta at 1/3, and weaker pd at ¼, and subapical circlet of short dorsal, ad, av, and pv setae; III: 2.2; 2.4; 0.5/ 0.6/ 0.4/ 0.3/ 0.2; FIII with strong anterior preapical seta; TIII with ad seta at ¼, 4–5 short dorsal setae along length, and subapical circlet of short dorsal, ad, av and pv setae.

Wing. Membrane hyaline, vein R 2+3 ending in costa near 5/6; vein M without flexion (bosse alaire) distad of juncture with crossvein dm-m; R 4+5 and M subparallel; vein M joining margin slightly posteriad of wing apex; CuAx ratio: 0.2; anal angle weak; lower calypter yellow with fan of brown setae; halter pale yellow.

Abdomen. Tergites and sternites dark brown, tergites 1–6 covered with brown vestiture, with some longer setae near tergite margins; tergites 1–4 with lateral abdominal plaques; segment 7 bare of setae and prolonged, acting as arm-like peduncle to protract genitalic capsule ( Fig 1b ), and retract under segment 6; sternite 8 subtriangular, with setae distally, with distinct median dorsoventral sclerotized band ( Figs 1b , 2b ), and forming cap over left basolateral hypopygial foramen; hypopygium ( Figs 1a, b , 2b ) mostly dark brown epandrium subrectangular; hypandrium forming flat elongate cover over phallus and apically curved ventrally; phallus projecting beyond hypandrium and curved ventrally; epandrium with four pedunculate setae along ventral margin as figured (arrows on Figs 1a, b ); epandrial lobe digitiform with two medially projecting tooth-like setae; ventral surstylar arm subrectangular; dorsal surstylar arm with apical toothlike seta (see arrow, Figs 1a, b ); cercus lobate and decumbent, with basal group of projecting pedunculated setae.

Female ( Fig. 2c ). Similar to male except as noted: face and clypeus wider; tergite 9+10 divided into two acanthophorites, each bearing 4 pointed spines or dornen; cercus subrectangular.

Remarks. Micromorphus caudatus as listed above is known from the West Indies and Central America. In Costa Rica, the species is known from elevations ranging from coastal lowlands to 1600 m.

I have not seen specimens of Micromorphus caudatus from the U.S.A. and records by Robinson (1964) as “ Micromorphus albipes ” from the states of Florida, South Carolina and Maryland need confirmation. Robinson noted that the specimens from Florida show numerous hairs on the tip of the hypopygium. Later, regarding specimens from Dominica, Robinson (1975) stated “ Some variation is recognized in the present concept of the species … Examination of the genitalia has been very difficult because of the minute size of the parts.” As noted above, great diagnostic detail is present in Micromorphus hypopygia, but is only visible once the male postabdomen is cleared and examined microscopically.

Figures

FIGURE 1. Micromorphus caudatus (Aldrich): a, male postabdomen, ventral; b, male postabdomen, left lateral. M. micidus Parent: c, male postabdomen, left lateral. Legend: cer, cercus; el, epandrial lobe; epand, epandrium; hyp, hypandrium; ph, phallus; st, sternite, tg, tergite; vsur, ventral surstylus. Arrows indicate position of diagnostic setae.

FIGURE 2. Micromorphus caudatus (Aldrich): a, male habitus, left lateral; b, male postabdomen, left lateral; c, female habitus, dorsal; M. micidus Parent; d, female postabdomen, dorsal; e, male habitus, left lateral; f, male wing, dorsal.