Terrobittacus angustus, Hua, 2017

Du, Wei & Hua, Bao-Zhen, 2017, Two new species of the genus Terrobittacus Tan & Hua, 2009 (Mecoptera: Bittacidae) from southwestern China with a key to species, European Journal of Taxonomy 294, pp. 1-13 : 7-10

Terrobittacus angustus sp. nov.

urn:lsid:zoobank.org:act:6279AC78-C9AA-4108-A537-F752F9B31318

Figs 5–8 , 9D

Diagnosis

The new species is distinguished from its congeners by the following characters: 1) wings with a clouded brown fleck along R 5 distally; 2) male epandrial appendages narrow, with small black spines on inner

surface of rounded apex; 3) female subgenital plate with a triangular membranous area basally and deeply cleft distally, two black sclerotized carinae at anterior portion.

Etymology

The specific epithet is derived from the Latin ‘ angustus ’ (narrow), referring to the narrow shape of the epandrial appendages in lateral view.

Type material

Holotype

CHINA: ♂, Yunnan Province, Yongde County, Mount Daxueshan , 24°01′30″ N, 99°15′15″ E, 1600– 2500 m, 21 Aug. 2015, Ji-Shen Wang leg. ( NWAU).

Paratypes

CHINA: 3 ♂♂, 3 ♀♀, same data as holotype, 21–23 Aug. 2015 ( NWAU).

Description

MEASUREMENTS. Male (n = 4): BL = 13.86 ± 0.61 mm; FL = 18.72 ± 0.34 mm, FW = 4.16 ± 0.13 mm; HL = 16.61 ± 0.32 mm, HW = 3.60 ± 0.16 mm. Female (n = 3): BL = 13.37 ± 0.38 mm; FL = 18.31 ± 0.36 mm, FW = 4.19 ± 0.15 mm; HL = 16.17 ± 0.49 mm, HW = 3.61 ± 0.12 mm ( Fig. 5A ).

HEAD. Vertex yellowish brown; frons dark brown; clypeus unevenly brown; genae pale yellow; labrum yellowish brown, with lateral edges darker; maxillary and labial palps brown; fourth maxillary palpomere slightly longer than fifth ( Fig. 5B ). Ocellar triangle black, median ocellus accompanied with two bristles and slightly smaller than others in diameter.Antennae filiform and ciliated; scape and flagellum yellowish brown, pedicel yellowish; flagellum ca 17-segmented and indistinctly segmented apically.

THORAX. Pronotum dark brown, with 2–4 long black setae along anterior edge, and few setae along posterior edge. Anterior two-thirds of mesonotum dark brown, the remaining portion and metanotum unevenly yellowish brown; meso- and metascutellum each with two long setae ( Fig. 5C ). Pleura unevenly pale brown, with scattered setae. Legs yellowish brown except coxae pale brown, femora and tibiae darker apically ( Fig. 5A ); fourth tarsomere with one spine on each side, hind basitarsus longer than second and third tarsomeres together.

WINGS. Forewing membrane hyaline and tinged with faint yellowish brown, costal margin and apical margin from pterostigma to R 5 slightly darkened; pterostigma conspicuous; brown clouded at ORs, FRs, OM and subdistal CuP, also along apical cross-veins; posterior portion of R 5 with a brown clouded fleck broadening toward apex; two thyridia each at FM and at base of M 4; apex of wing almost right-angled and outer margin from R 5 to M 3 straight; one Pcv; Sc ending beyond level of FRs; CuA ending at level of Sc terminus; CuP ending before level of Scv; Cuv before level of FM; 1A ending at level of ORs, or slightly beyond level of ORs; Av absent; apical cross-veins roughly arranged in two lines; cross-veins between M 2 to M 4 transparent. Hindwings similar to forewings, but Sc terminated before FRs, 1A and CuP coalesced subbasally ( Fig. 6 ).

ABDOMEN OF MALE. Terga II–VIII yellowish brown to dark brown, each with a black narrow antecosta; tergum VIII slightly emarginated on posterior margin. Sterna II–VI pale yellow, sterna VII–IX yellowish brown. Pleura pale. Epandrial appendages rather narrow, clavate in lateral view, broad basally and narrowing toward rounded apex, and distinctly shorter than half of gonocoxites ( Fig. 7A ); inner surface with a patch of small black spines apically ( Fig. 7B ). Tergum X vestigial dorsally, with two lateral plates extending to and surrounding bases of cerci. Upper branch of proctiger strongly sclerotized and with two lateral flanks bearing scattered short setae, its apex slightly curved into a hook; lower branch of proctiger curved downward and shorter than upper branch ( Fig. 7C ). Cerci dark brown and slightly curved apically, slightly shorter than epandrial appendages. Gonocoxites yellowish brown dorsally and dark brown ventrally, completely joined ventrally and with a V-shaped membranous area posteriorly ( Fig. 7A, D ); in one specimen, gonocoxites separated by a rather narrow membranous area in ventral aspect. Gonostyli setose and tapering toward apex. Aedeagus with two acute aedeagal lobes each projecting a triangular process from anterior margin mesally; penisfilum greatly elongated, coiled ( Fig. 7A, D ).

ABDOMEN OF FEMALE. Terga II–IX unevenly dark brown, each with narrow black antecosta. Sterna II–VII pale yellow to yellowish brown. Subgenital plate yellowish brown with pale triangular membranous area basally, and deeply cleft apically; lateral margins oval at basal half, and each projecting a slender process extending to anterior edge of tergum IX distally ( Fig. 8A ); subgenital plate with long thick setae at posterior portion, and a pair of black carinae at anterior portion ( Fig. 8B ). Tergum X yellowish brown and extending ventrad. Supraanal plate and subanal plate truncated apically with long setae, posterior edge of supraanal plate with a small process mesally.

Distribution

Yunnan Province, China.

Remark

Terrobittacus angustus sp. nov. is similar to T. rostratus sp. nov. in the general coloration and wing venation, but its wings have clouded markings at forks of major veins, along most apical cross-veins and the distal half of R 5 (cf. wings devoid of markings). They can also be readily separated by the external genitalia, for T. angustus sp. nov. has male epandrial appendages clavate in lateral view (cf. epandrial appendages boot-shaped), and female subgenital plate lacking a narrow membranous line mesally (cf. subgenital plate with the membrane in mesal line).

Figures

Fig. 5. Terrobittacus angustus sp. nov. A. ♂, habitus in lateral view. B. Head in frontal view. C. Thorax in dorsal view. Abbreviations: Ant = antenna; Cly = clypeus; Fr = frons; Lr = labrum; MP = maxillary palp. Scale bars: A = 5.0 mm; B = 0.2 mm; C = 0.5 mm.

Fig. 6. Right wings of a male specimen of Terrobittacus angustus sp. nov. Scale bar = 2.0 mm.

Fig. 7. Male genitalia of Terrobittacus angustus sp. nov. A. Terminalia in lateral view. B. Epandrial appendages in dorsal view. C. Abdominal segment X and proctiger in lateral view. D. Genitalia in caudal view. Abbreviations: AL = aedeagal lobe; Ce = cercus; EA = epandrial appendage; Gcx = gonocoxite; Gs = gonostylus; LBP = lower branch of proctiger; Pf = penisfilum; S = sternum; Sp = spiracle; T = tergum; UBP = upper branch of proctiger. Scale bars: A = 0.5 mm; B–D = 0.2 mm.

Fig. 8. Female terminalia of Terrobittacus angustus sp. nov. A. Lateral view. B. Ventral view. Abbreviations: Ce = cercus; SaP = subanal plate; SgP = subgenital plate; Sp = spiracle; T = tergum. Scale bars = 0.5 mm.

Fig. 9. Habitats of Terrobittacus spp. A–B. Habitats. C. Female specimen of T. rostratus sp. nov. in repose. D. Female specimen of T. angustus sp. nov. in repose. (photos by Ji-Shen Wang)