Silba filamenta MacGowan et Barták, 2022

MacGowan, I. & Barták, M., 2022, An annotated list of Lonchaeidae (Diptera) from China, Cambodia and Vietnam with description of a new species, Far Eastern Entomologist 447, pp. 10-16 : 12-14

Silba filamenta MacGowan et Barták , sp. n.

http://zoobank.org/NomenclaturalActs/ B8A216F3-7DEA-4899-96FC-F0AAF8E4D1D1

Figs 1–4

TYPE MATERIAL. Holotype – ♂, China: Jilin Province, Jiaohe env. 95km NNE of

Jillin, 43°95’N, 127°7’E, alt.= 400–600 m, 27. VI – 5.VII 2017, leg. E. Jendek & O. Šauša.

Specimen number NMS-10005732 (deposited in NMS). Paratype – China: Jilin Province ,

Erdaocum, 42°42’N, 128°07’E, alt.= 800 m, 25–26.VI 2017, 1 ♂, leg. E. Jendek & O.

Šauša (deposited in CULSP).

DESCRIPTION. MALE: Body length 4.0mm.

Head: Eyes bare. Frons dull black covered with a light grey pollinosity, narrowing only slightly from level of ocellar triangle to antennal bases where it is 0.5x eye width. Orbital plate dulled by microsculpture, bare apart from the orbital seta. Interfrontal and frontal setulae approximately 0.25x length of orbital seta. Lunule black, face and parafacials light grey pollinose Antennae black, postpedicel length to depth ratio 2.5:1. Arista short plumose,

plumosity at maximum extent 0.5x depth of postpedicel. Anterior genal setulae in a single row of four along mouth edge, these slightly separate from the other genal setulae the basal setula of this row the strongest on the genae.

the same, ventral view; 3 – inner surface of surstylus, internal view; 4 – phallus, lateral view.

Thorax: scutum sub–shining blue black, covered with setulae approximately 0.5x length of orbital seta. Anepisternum with five anterior setae and six posteriorly, area between these lines of setae with numerous scattered setulae approximately 0.5x as long as the longest seta.

Katepisternum, two strong setae situated near dorsal margin, the posterior slightly longer and stronger than the anterior. Scutellum slightly damaged with some setae and setulae missing,

apparently 2 setulae between apical setae and eight in a partly multiserial row between apical and lateral seta. Calypteres; greyish, with fringe dark, long and dense. Wings slightly fumose,

especially towards base, veins brownish, wing length 4.1mm. Legs entirely black.

Male terminalia: In lateral view epandrium slightly wider than high, with a scattering of long setae along posterior and ventral margins. Cerci rather square in shape, approximately

0.4x height of epandrium, with a fringe of long setulae along posterior and ventral margins.

Surstyli entirely contained within shell of epandrium. In ventral view ventral margins of the surstyli with a regular row of long, strong setae. Pregonites rather pointed at apex, postgo-

nites with apical margin setulose. Internal surface of surstyli with a row of eight prensisetae,

a line of five larger prensisetae along posterior margin reaching from base of cerci to ventral margin, the most ventral of these slightly separated from the rest, three smaller prensisetae continuing this line along ventral margin. A strong seta and several setulae located between the base of the cerci and the row of prensisetae. Inner surface of surstyli medially with 3–4

lateral grooves, anteriorly the surstyli developed into a long sinuous projection which curves back posteriorly.

Phallus, basiphallus roughly square in shape with an extended dorsal projection, disti-

phallus arising postero-ventraly, slightly curved, almost as long as depth of basiphallus. Two long, slightly curved basal projections arising anteroventrally from the basiphallus, these longer than the total width of the basiphallus, bearing several long spicules basally. A number of long, thin filaments arising from the ventral surface of the basiphallus, some of these simple, others branched.

FEMALE unknown.

DIAGNOSIS. With entirely black legs and calypteres darkened with a dark fringe this species is externally similar to the majority of Silba species known from the Oriental and

Eastern Palearctic realms. The relatively short aristal plumosity is also typical of Silba species whose range is near the northern limit of this mainly tropical genus. As a result of this external similarity Silba species can only be confidently identified to species level by examination of the male terminalia. In this case the highly distinctive phallus with its numerous filamentous projections immediately distinguishes it from any other described species.

DISTRIBUTION. China (Jilin).

ETYMOLOGY. The specific epithet refers to the filaments on the basal part of the phallus.

Figures

Figs 1–4. Silba filameta sp. n. 1 – epandrium and associated structures, lateral view; 2 –