Myolepta geras, 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 : 103-106

Myolepta geras sp. nov.

urn:lsid:zoobank.org:act:BA8D954A-E641-4FD0-9093-91A5B4E362C2

Fig. 4

Diagnosis

Myolepta geras sp. nov. has short antenna, shorter than face, with postpedicel less than 2× longer than broad ( Fig. 4C ). Face black, shiny medially, with grey pruinosity along the eye margin ( Fig. 4C ). Black scutum with adpressed black hairs mixed with yellow scale-like hairs. Legs bicolorous ( Fig. 4A ). Cell r 4+5 distinctly petiolate; vein R 4+5 with last section longer than crossvein h ( Fig. 4B ). Abdomen parallel-sided, tergites 2 and 3 black, pruinose, with two elongated orange maculae on anterior margin not reaching the posterior margin, and tergite 4 black with posterior margin brown, shiny except a medial brown pruinose macula on anterior margin ( Fig. 4A–B ).

Differential diagnosis

Myolepta geras sp. nov. differs from other Indomalayan species of Myolepta (except Myolepta iota sp. nov.) by the presence of scale-like hairs on the scutum and pleuron ( Fig. 4A–B ), and by the cell r 4+5 distinctly petiolate, with petiole longer than crossvein h ( Fig. 4B ). It differs from Myolepta iota sp. nov. by the coloration of the legs (see identification key), the shiny anterodorsal part of the anterior anepisternum not covered with scale-like hairs (grey pruinose in Myolepta iota sp. nov.), the absence of scale-like hairs on scutellum (present in Myolepta iota sp. nov.), abdominal pattern, and the membrane between tergites and sternites partly black (entirely yellow in Myolepta iota sp. nov.). Male genitalia quite similar to those of Myolepta iota 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 ‘γῆρᾰς’(‘ gêras ’), meaning ‘old age’ ( Brown 1956: 569); it refers to the age of the specimen, which was collected 90 years ago. Species epithet is to be treated as a name in apposition.

Type locality

Indonesia: West Java, Dungus Iwul [Nature Reserve], [6.523347° S, 106.418324° E], alt. 100 m.

Material examined

Holotype INDONESIA • ♂; West Java Province, Dungus Iwul [Nature Reserve]; [6.523347° S, 106.418324° E]; alt. 100 m; 4 Nov. 1932; M.A. Lieftinck leg.; NBC; ZFMK-DIP-00082513 .

Description

MEASUREMENTS. Body: 7.2 mm; wing: 6.0 mm.

Male

HEAD ( Fig. 4A, C ). Face with small facial tubercle, bare medially, shiny black, densely silvery pruinose laterally along eye margin from the antennal insertion to gena (pruinosity continuing until the 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 black, dark brown medially. Frontal triangle shiny black on ventral ½, silvery 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 longer than frontal triangle. Antenna yellow; scape and pedicel with yellow hairs and 2 and 3 brown setulae dorsally, respectively; postpedicel furry-like, rounded apically, slightly longer than broad. Arista bare, brown. Vertical triangle black, shiny, with adpressed yellow setulae. Occiput covered with silvery pruinosity (except the posterior margin of vertical triangle), with white hairs ventrally and scattered short, black setulae along margin, more abundant on dorsal ⅓.

THORAX ( Fig. 4–B ). Scutum black, densely grey pruinose anteriorly, including anterior ½ of postpronotum, lightly grey pruinose on notopleuron. Postalar callus and posterior part of postpronotum brown. Scutum with adpressed black hairs mixed with scale-like hairs, which are dark yellow and more dense anterior to transverse suture and white and more scattered posterior to transverse suture. Short black setulae on supra-alar area. Scutellum rounded, black, without subscutellar fringe, with adpressed yellow hairs; posterior margin with short black setulae with thick, expanded alveolus, making posterior margin to look serrate. Pleuron black, with grey dense pruinosity on proepisternum and proepimeron; with white scale-like hairs on posterodorsal part of anterior anepisternum, posterior anepisternum, dorsal part of katepisternum and anterior anepimeron (posterior anepimeron with 1–2 white scale-like hairs anteriorly); anatergum with yellow hairs, lightly grey pruinose. Plumule yellow, very short. Metaepisternum and metasternum bare. Halter yellow, brownish basally. Posterior spiracular fringes dark yellow to brown.

WINGS. Membrane hyaline; pterostigma yellow; extensively microtrichose except cell c on basal ¼, cell br anterior to RS bifurcation, and cells bm and cua on basal ¾. 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 h and slightly shorter than crossvein r-m.

LEGS. Coxae black (fore coxa yellowish ventrally), partly lightly grey pruinose; trochanters yellow. Fore femur incrassate, yellow except black on apex forming subapical black ring, with yellow hairs and two rows of short black setae on ventral side; fore tibia yellow on basal ⅔, black on apical ⅓, yellow hairy with black setulae on ventral side; basal three fore tarsomeres black with dorsal part yellow, black hairy dorsally and yellow hairy ventrally with some black setulae; apical two fore tarsomeres black with yellow hairs; apical tarsomere yellowish at apex. Mid femur slightly swollen, yellow except black on apex forming a subapical black ring, 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 4–5 long (half as long as femur’s width), yellow setae on dorsal side; hind tibia yellow on basal ½, black on apical ½, yellow hairy with black setulae on ventral side; hind basitarsomere yellow, black and yellow hairy dorsally and yellow hairy ventrally.

ABDOMEN ( Fig. 4A–B ). Parallel-sided, unmargined. Tergite 1 black, grey pruinose, yellow-white hairy. Tergite 2 black, with two lateral elongated orange maculae on anterior margin not reaching lateral or posterior margins, lightly grey pollinose (clearly visible along anterior margin), with adpressed black hairs medial and laterally, with a group of 6–7 long, yellow setae on anterolateral margin. Tergite 3 black, with two lateral elongated orange maculae on anterior margin not reaching lateral or posterior margins, lightly grey pollinose (clearly visible along anterior margin) but shiny on posterior margin and lateral margins, with adpressed black hairs medial and laterally. Tergite 4 black, shiny with some light grey pruinose on anterior margin, with adpressed golden-brownish hairs. Sternites black except sternites 2 and 3 brown, with short yellow hairs, shiny except sternite 1 entirely grey pruinose and sternite 4 with medial grey pruinose vitta. Membrane between tergites and sternites 2 and 3 black, between tergite and sternite 4 yellow.

MALE GENITALIA. As in Fig. 4D–I . Epandrium subquadrate ( Fig. 4E ); surstylus with dorsal margin undulate with strong setae ( Fig. 4F ); hypandrium with 4–5 strong and thick setae on lateral and dorsal medial portion ( Fig. 4D, H ).

Remarks

The original label states “Dungus Iwul” as the sampling locality of the holotype, and I assume this refers to the Dungus Iwul Nature Reserve in West Java province. This is the single species of Myolepta known from Indonesia, representing the southernmost record of this genus in the Indomalayan Realm.

Figures

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.