Sciasmomyia decussata, Shi, Li, Gaimari, Stephen D. & Yang, Ding, 2013

Shi, Li, Gaimari, Stephen D. & Yang, Ding, 2013, Revision of Sciasmomyia Hendel (Diptera: Lauxaniidae), with eight new species, Zootaxa 3691 (4), pp. 401-435 : 404-407

Sciasmomyia decussata sp. nov.

( Figs 1–11 )

Diagnosis. Face with a pair of brown irregular spots between antennae, a brown round median spot, a brown triangular spot at ventral corner and a brown irregular median spot on ventral margin; parafacial pale yellow except for inner margin brown, with a blackish brown elliptical spot at ventral corner. Palpus brown except for pale yellow on apical 1/3–1/2. Mesonotum slightly grayish brown on anterior 1/2 between two dc rows, with pair of brown spots and pair of brown median stripes; anepisternum with three irregular brown spots, katepisternum with two irregular brown spots near upper margin. Wing with ultimate section of M1 with rectangular hyaline spot constricted at middle and C-shaped hyaline apical spot. Abdomen yellow with sparse grayish white pruinosity. Male with epandrium very broad in lateral view; phallus with pair of small triangular subapical processes curled outwards and pair of decussating apical processes in ventral view. Female with hypogynial valve trapezoidal with dense setulae in ventral view.

Description. MALE. Body length 4.9 mm, wing length 5.3 mm. FEMALE. Body length 4.3 mm, wing length 5.3 mm.

Head ( Fig. 2 ) pale yellow. Frons with two narrow brown stripes extending to ocellar triangle; ocellar triangle black; oc longer than posterior or. Face with a pair of brown irregular basal spots between antennae, a brown round median spot, a brown triangular spot at ventral corner and a brown irregular median spot on ventral margin; parafacial pale yellow except for inner margin brown, with a blackish brown elliptical spot at ventral corner and three long setulae under the elliptical spot. Gena about 1/2 height of eye, with a pale brown spot. Antenna pale yellow, 1st flagellomere with a pale brown spot at base of arista, 1st flagellomere 1.1 times longer than high; arista with longest setula shorter than 1/3 height of 1st flagellomere. Proboscis yellow. Palpus brown except for pale yellow on apical 1/3–1/2.

Thorax ( Fig. 3 ) yellow. Mesonotum slightly grayish brown on apical 1/2 between two dc rows, with two brown spots and a pair of brown median stripes; anepisternum with three irregular brown spots, katepisternum with two irregular brown spots near upper margin. Legs pale yellow. Fore femur with 5 pv and 6 pd; mid femur with 2 weak a; hind femur with 1 weak preapical ad. Wing ( Fig. 4 ) pale brown with hyaline spots, all of which display white on that part of the vein; series of longitudinal spots along costal margin extending through R2+3, along R4+5, and along CuA1; small hyaline spot present between each longitudinal spot along R2+3; ultimate section of M1 with rectangular hyaline spot constricted at middle and C-shaped hyaline apical spot; crossvein r-m pale brown, incompletely surrounded by hyaline area (except below); costa with 2nd (between R1 and R2+3), 3rd (between R2+3 and R4+5) and 4th (between R4+5 and M1) sections in proportion of 5.2:1.4:1; ultimate and penultimate sections of M 1 in proportion of 1:1.6; ultimate section of CuA1 about 1/10 of penultimate. Halter yellow except for knob pale brown on basal 1/2.

Abdomen yellow with sparse grayish white pruinosity. Male genitalia ( Figs 5–8 ): syntergosternite 7+8 degenerate into two narrow lateral sclerites confluent with epandrium, spiracle present on sclerite; surstylus nearly triangular, with setulae; hypandrium convergent apically with two rectangular apical processes; phallus with a pair of small triangular subapical processes curled outwards and a pair of decussating apical processes in ventral view; phallapodeme (fused to phallus) narrow, slightly bulging at middle in ventral view. Female terminalia ( Figs 9–11 ): epiproct nearly rectangular, hypoproct with a small apical incision in lateral view; hypogynial valve trapezoidal with dense setulae in ventral view.

Type material. Holotype 3 (CAUC): CHINA, Guizhou Province: Fanjingshan, Huguosi, 1350–1550 m, 28. VII. 2001, Wanzhi Cai. Paratype: CHINA, Guizhou Province: Fanjingshan, Huguosi, 1400 m, 28. VII. 2001, Xinwei Niu (1Ƥ, CAUC).

Distribution. China (Guizhou).

Remarks. The new species is distinguishable from other species by characteristics of the wing, and of male and female genitalia.

Etymology. Latin, decussata , meaning crossing, decussating; referring to the phallus with a pair of decussating apical processes; a feminine adjective.

Figures

FIGURES 1 – 4. Sciasmomyia decussata sp. nov. Holotype male. 1. habitus, lateral view; 2. head, anterior view; 3. thorax, dorsal view; 4. wing.

FIGURES 5 – 11. Sciasmomyia decussata sp. nov. Holotype male. 5. syntergosternite 7 + 8 and epandrial complex, lateral view; 6. syntergosternite 7 + 8 and epandrial complex, posterior view; 7. phallus complex, ventral view; 8. phallus complex, lateral view. Paratype female. 9. abdominal tergites and sternites 7 – 9, lateral view; 10. hypogynial valve, ventral view; 11. spermathecae. Scale 0.1 mm.