Micromorphus micidus Parent, 1937

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 : 442-444

Micromorphus micidus Parent

( Figs 1c ; 2d–f )

Micromorphus micidus Parent, 1937: 130 .

Type material. Parent described Micromorphus micidus based on males and females collected in “Costa Rica” ( ZMUH, types destroyed). NEOTYPE ♂, here designated: COSTA RICA: Alajuela: Reserva Forestal Arenal , Send. Pilón, 650 m, 18.v.1999 – 26.vi.2000, G. Carballo, Malaise, L.N. 269200 458040, #56832 ( INBIO).

Additional material. COSTA RICA: Alajuela: ♂, ♀ with same data as neotype. ( INBIO) . Heredia: ♂, 10 km W of Pto. Viejo, Selva Verde , 2–6.iii.1991, B.J. Sinclair ( CNC) . Limon: 20 ♂, 8 ♀, Ambrui, Talamanca , 18– 26.vii.1975, W.G. Hanson ( USU, deposited LACM) ; 3 ♂, 2 ♀, Sector Cocori, 30 km al Norte de Cariari , A.C. Tortuguero, 100 m, 22.ix–23.xi.1999, Malaise, L.N. 286000 567500, #2436 ( INBIO) ; ♂, Estrella Valley, Pandora , 28.iii.1984, G. Manley ( DEBU) . Puntarenas: ♂, Lepanto, Reserva Priv. Karen Morgensen, Quebrada Pérez , 315 m, 22.vi–10.vii.2003, W. Porras, Malaise #1, L.N. 205300 419750 ( INBIO) . GUATEMALA: 34 ♂ 17 ♀, Las Escobas, 200 m, 14–16.xi.1986, Malaise trap, M. Sharkey ( CNC) .

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

Head. Head ovate, higher than wide; dorsal postcranium 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 antennal base; 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 subtriangular, with fine brownish hairs, and arista-like stylus apical and slightly longer than head height.

Thorax. Mostly dull dark brown; posterior mesonotum flattened; setae brown; ac absent; 4 strong dc present, posteriormost dc (adjacent to flattened area) slightly offset laterally; 1 pa, 2 sa, 1 sr, 2 npl, 1 hm, 1 pm present; median scutellar setae strong, laterals absent; lower proepisternum with short whitish seta.

Legs. CI yellow, CII and CIII brown basally but yellow distally; trochanters and legs mostly yellow, but femora II and III infuscated and brownish; CI and CII with short brownish anterior setae; CIII with dark brown lateral seta near ½; legs with short brown vestiture; I: 1.7; 1.5; 0.8/ 0.7/ 0.4/ 0.3/ 0.2; leg I bare of major setae; II: 1.9; 2.2; 1.0/ 0.7/ 0.4/ 0.3/ 0.2; FII with strong anterior preapical seta; TII with strong dorsal seta at 1/3, and subapically; III: 2.2; 2.3; 0.3/ 0.8/ 0.4/ 0.3/ 0.2; FIII with strong anterior preapical seta; TIII with short dorsal setae and subapical circlet of dorsal, ad seta at ¼ and ¾, 4–5 short dorsal setae along length, and subapical circlet of strong 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 and slightly bowed in distal third of wing; vein M joining margin slightly posteriad of wing apex; CuAx ratio: 0.4; anal angle weak; lower calypter yellow with fan of brown seta; halter pale yellow.

Abdomen. Tergites and sternites dark brown, tergites 1–6 covered with brown vestiture, with some longer setae near tergal margins; segment 7 short, not forming narrow pedicel; sternite 8 ovate, with scattered setae and forming cap over left basolateral hypopygial foramen; hypopygium ( Fig. 1c ) mostly dark brown; epandrium ovate; epandrial seta arising from inside epandrial chamber near midlength and with strong setae distad on ventral margin of epandrium; hypandrium forming flat elongate cover over phallus and apex curved ventrally; epandrial lobe short, and internal, mediad of surstylus; phallus projecting beyond hypandrium; surstylus lobate with marginal indentations and bearing setae as figured; cercus lobate and subtriangular, with abundant setae.

Female ( Fig. 2d ). Similar to male except as noted: lower face and clypeus wider; tergite 9+10 divided into two acanthophorites, each bearing 4 pointed spines or dornen; cercus slightly tapering in dorsal view.

Remarks. Micromorphus micidus is known from Costa Rica and Guatemala and is probably widespread in Central America.

Robinson (1967, 1970) correctly noted that this species differed from other Micromorphus species in wing venation (having veins M and R 4+5 distally bowed with respect to each other, Fig. 2f ), antenna (arista apical, rather than dorsal and in slight depression as in other Micromorphus ), and that the male postabdomen lacks an elongate pedunculated segment 7 like other Micromorphus (e.g., compare Figs 1a and 1c ), which was inaccurately figured by Parent (1937, fig. 41). Also there are only 4 dc setae, whereas most Micromorphus have 5 dc.

Robinson (1970) suggested that Micromorphus micidus should be placed in a separate new genus. However, the species is rather “nondescript” and not so strongly defined to represent a new genus on its own. If interpreted broadly, Micromorphus could include the species, and without further information or additional closely related species, I prefer to keep M. micidus in the genus.

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.