Myolepta iota, Mengual, 2022

Mengual, Ximo, 2022, New species of Myolepta Newman, 1838 (Diptera, Syrphidae) from the Indomalayan Realm, European Journal of Taxonomy 833, pp. 97-120 : 106-109

Myolepta iota sp. nov.

urn:lsid:zoobank.org:act:261854F9-52BC-4262-BB21-FF61375E3501

Fig. 5

Diagnosis

Species with short antenna, shorter than face, with postpedicel less than 2× as long as broad ( Fig. 5C ). Face black, shiny medially, with grey pruinosity along the eye margin. Black scutum with adpressed black hairs mixed with yellow scale-like hairs ( Fig. 5B ). Legs bicolorous ( Fig. 5A ). Cell r 4+5 distinctly petiolate; vein R 4+5 with last section longer than crossvein h ( Fig. 5B ). Abdomen almost parallel-sided, tergites 1–3 brown, brown pruinose, tergite 4 black with posterior margin brown, shiny except a medial brown pruinose macula on anterior margin ( Fig. 5B ).

Differential diagnosis

Small species of Myolepta that differs from other Indomalayan species of Myolepta (except Myolepta geras sp. nov.) by the presence of scale-like hairs on scutum, pleuron and scutellum, and by the cell r 4+5 distinctly petiolate, with petiole longer than crossvein h. It differs from Myolepta geras sp. nov. by the coloration of the legs (see identification key), the grey pruinosity on the anterior part of the anterior anepisternum not covered with scale-like hairs (shiny in Myolepta geras sp. nov.), the presence of scale-like hairs on scutellum (absent in Myolepta geras sp. nov.), and the membrane between tergites and sternites entirely yellow (partly black in Myolepta geras sp. nov.). Male genitalia quite similar to those of Myolepta geras sp. nov., but different in the dorsal margin of the surstylus and the size and arrangement of the lateral setae on the hypandrium (see Figs 4–5 ).

Etymology

From Greek ‘ἰῶτα’ (‘ iôta ’), the name of the ninth letter of the Greek alphabet and used to name anything very small ( Brown 1956: 488). Species epithet is to be treated as a name in apposition.

Type locality

Thailand: Mae Hong Son Province, Ban Huai Po, [19.4246° N, 97.9148° E], alt. 480 m.

Material examined

Holotype THAILAND • ♂; Mae Hong Son Province, Ban Huai Po ; [19.4246° N, 97.9148° E]; alt. 480 m; 1–5 May 1992; Stmad leg.; NMP; ZFMK-DIP-00082514 .

Paratype THAILAND • 1 ♂; same collection data as for holotype; ZFMK; ZFMK-DIP-00082515 .

Description

MEASUREMENTS. Body: 5.0– 5.2 mm; wing: 4.2–4.5 mm.

Male

Head ( Fig. 5C ). Face with a small facial tubercle, bare medially, shiny black, densely silvery pruinose laterally along eye margin from antennal insertion to gena (pruinosity continuing until occiput) with scattered thick white hairs, and lightly grey pruinose above antennal insertion. Gena narrow, shiny black and bare ventrally, dorsally completely silvery pruinose and with scattered thick white hairs. Lunule shiny brown. Frontal triangle shiny black on ventral ½, silvery-grey pruinose on dorsal ½; pruinosity from dorsal part of frontal triangle not joining with lateral pruinosity of face. Eye bare, with slightly enlarged ommatidia on dorsofrontal part; holoptic. Eye contiguity as long as frontal triangle. Antenna yellow; scape and pedicel with yellow hairs; pedicel with 3 brown setulae dorsally; postpedicel furry-like, rounded apically, longer than broad. Arista bare, brown. Vertical triangle black, shiny, with adpressed yellow setulae. Occiput covered with silvery pruinosity (except the posterior margin of the vertical triangle), with white hairs ventrally and scattered short, black setulae along margin, more abundant on dorsal ⅓.

THORAX ( Fig. 5A–B ). Scutum black, densely grey pruinose anteriorly, including anterior ½ of postpronotum. Postalar callus brown. Scutum with adpressed black hairs mixed with yellow scale-like hairs. Short black setulae on supra-alar area. Scutellum rounded, black, without subscutellar fringe, with adpressed yellow hairs mixed with yellow scale-like hairs; posterior margin with short black setulae with thick, expanded alveolus, making the posterior margin to look serrate. Pleuron black, with grey dense pruinosity on proepisternum, proepimeron and anterior bare part of the anterior anepisternum; with white scale-like hairs on posterodorsal part of the anterior anepisternum, posterior anepisternum, dorsal part of katepisternum and anterior anepimeron (posterior anepimeron with 2–3 white scalelike hairs anteriorly); anatergum with yellow hairs, lightly grey pruinose. Plumule yellow, very short. Metaepisternum and metasternum bare. Halter yellow. Posterior spiracular fringes yellow.

WINGS. Membrane hyaline; pterostigma yellow; extensively microtrichose except cell c on basal ⅓, cell br anterior to RS bifurcation, cell bm on basal ¾ and cell cua on basal ½. Spurious vein absent. Vein RS and basal section of R with black setulae dorsally. Cell r 4+5 petiolate; vein R 4+5 with last section longer than crossvein r-m.

LEGS. Coxae black; fore coxa densely grey pruinose; trochanters yellow. Fore femur incrassate, yellow on basal ½–3/5 and black on apical 2 /5–½, with apex yellow, with yellow hairs and two rows of short black setae on ventral side; fore tibia yellow on basal ⅔ with black elongated macula on posterior side, black on apical ⅓, yellow hairy with black setulae on ventral side; basal three fore tarsomeres yellow with black hairs dorsally, black with yellow hairs ventrally; apical two fore tarsomeres black with yellow hairs. Mid femur slightly swollen, yellow on basal 4 /5 and black on apical 1 /5, with yellow hairs and two rows of short black setae on ventral side; mid tibia yellow, yellow hairy with black setulae on ventral side; basal three mid tarsomeres yellow, apical two mid tarsomeres black, black hairy dorsally and yellow hairy ventrally with some black setulae. Hind femur yellow on basal ⅓, black on apical ⅔, yellow hairy with two rows of short black setae on ventral side, and long (half as long as femur’s width) black setae on the dorsal side; hind tibia yellow on basal ⅔, black on apical ⅓, yellow hairy with black setulae on ventral side; basal three hind basitarsomeres yellow, yellow hairy, and apical two hind basitarsomeres black, black and yellow hairy.

ABDOMEN ( Fig. 5A–B ). Almost parallel-sided, with the maximum width between tergites 3 and 4, unmargined. Tergite 1 dark brown, brown pruinose, yellow hairy; tergite 2 broader than long, brown with diffuse yellow fascia on anterior margin broadening laterally, brown pruinose, yellow hairy with tuft of long yellow setae on anterolateral corner; tergite 3 brown becoming black posteriorly with diffuse yellow marking on anterior margin, brown pruinose, yellow hairy; tergite 4 black with posterior margin brown, shiny except medial, triangular brown pruinose macula on anterior margin, yellowish brown hairy. Sternites with addressed yellow hairs; sternite 1 dark brown to black, densely grey pruinose; sternite 2 dark brown medially and yellow laterally; sternite 3 dark brown with two yellow macula anterolaterally; sternite 4 dark brown. Membrane between tergites and sternites entirely yellow.

MALE GENITALIA. As in Fig. 5D–I . Epandrium subquadrate; surstylus with dorsal margin strongly undulate forming two clear lobes, with strong setae ( Fig. 5F ); hypandrium with 4–5 small and thin setae at margin (on rim) between dorsal and lateral parts plus three additional small setae at lowest part of this rim in the dorsal part.

Remark

I assume that these specimens were collected with a Malaise trap, based on the sampling dates, and that it co-occurs with Myolepta petiolata .

Figures

Fig. 5. Myolepta iota sp. nov., ♂, holotype (ZFMK-DIP-00082514). A. Habitus, lateral view.B. Habitus, dorsal view. C. Head, frontal view. D. Genitalia, hypandrium, lateral view. E. Genitalia, epandrium, lateral view. F. Genitalia, epandrium, dorsoposterior view. G. Genitalia, epandrium, ventral view. H. Genitalia, hypandrium, dorsal view. I. Genitalia, hypandrium, ventral view. Scale bars: A–B =1 mm; C=0.5 mm; D–I =0.1 mm.

Fig. 4. Myolepta geras sp. nov., ♂, holotype (ZFMK-DIP-00082513). A. Habitus, lateral view. B. Habitus, dorsal view. C. Head, frontal view. D. Genitalia, hypandrium, lateral view. E. Genitalia, epandrium, lateral view. F. Genitalia, epandrium, dorsoposterior view. G. Genitalia, epandrium, ventral view. H. Genitalia, hypandrium, dorsal view. I. Genitalia, hypandrium, ventral view. Scale bars: A–C=1 mm; D–I =0.1 mm.