Gonioctena (Gonioctena) metallica Cho & Borowiec

Cho, Hee-Wook & Borowiec, Lech, 2014, Two new species of the genus Gonioctena Chevrolat (Coleoptera, Chrysomelidae, Chrysomelinae) from Sichuan, China, Zootaxa 3765 (3), pp. 295-300 : 298-300

Gonioctena (Gonioctena) metallica Cho & Borowiec , sp. n.

( Figs 2, 4 , 8–9 , 11 )

Type material. Holotype: male ( NHMB), China: Sichuan, Tatsienlu-Kiulung [ Tatsienlu = recent Kangding ], Reitter . Paratypes: 2 males and 1 female, same data as holotype.

Diagnosis. This new species is very similar to G. yunnana Medvedev occurring in Yunnan, China in having metallic lustre on head and pronotum, reddish brown elytra and very long aedeagus. This combination of characters is unique in the genus Gonioctena and both species are distributed in southwestern China. However, G. metallica sp. n. can be distinguished by its generally larger body size (5.0– 6.1 mm in G. yunnana ), elytra with regular rows of large punctures (partly irregular in G. yunnana ), apical process of aedeagus swollen apically in dorsal view (very long and straight in G. yunnana ) and apex of aedeagus curved in lateral view (slightly sinuate in G. yunnana ( Fig. 10 )). G. japonica Chûjô et Kimoto also has similar shape of aedeagus, but differs in reddish brown body with black spots on pronotum and elytra.

Description. Measurements in mm (n = 4): length of body: 6.00–6.60 (mean 6.23); width of body: 3.50–3.90 (mean 3.63); height of body: 2.20–2.40 (mean 2.28); width of head: 1.65–1.75 (mean 1.73); interocular distance: 1.25–1.30 (mean 1.27); width of apex of pronotum: 1.95–2.00 (mean 1.98); width of base of pronotum: 3.00–3.10 (mean 3.03); length of pronotum along midline: 1.45–1.47 (mean 1.47); length of elytra along suture: 4.40–4.90 (mean 4.56).

Body ( Fig. 2 ) oblong and weakly convex dorsally. Head metallic blackish green. Mandibles black, narrow dark reddish brown band near apex. Maxillary palp blackish brown with apical palpomere black. Antennomeres 1–5 brown to dark brown, 6–7 blackish brown, 8–11 black. Pronotum metallic blackish green. Scutellum black. Elytra bright reddish brown. Venter black with each abdominal sternite reddish brown apically. Legs black, tibiae reddish brown except base and inner margin, tarsi dark brown to blackish brown.

Head. Vertex with sparse to moderately dense and small punctures. Frons rather flat, suddenly depressed anteriorly, with moderately dense and small punctures. Clypeus trapezoid with several long setae. Labrum almost straight anteriorly with several long setae. Mandibles asymmetrical; right mandible with an excavation for apical teeth of left mandible; each with 2 sharp apical teeth, a large excavation for maxillary palp at outer side. Maxillary palp 4-segmented with apical palpomere strongly widened in male; slightly widened in female. Antennae ( Fig. 8 ) reaching base of pronotum; antennomere 1 robust, longer than 3; antennomere 2 slightly longer than 3; antennomere 3 distinctly longer than 5; antennomeres 7–10 distinctly widened, each slightly longer than wide; antennomere 11 twice as long as wide.

Pronotum ( Fig. 4 ). Lateral sides widest at or near base, roundly narrowed anteriorly. Anterior margin widely emarginate. Anterior and lateral margins bordered. Lateral margins hardly or weakly visible in dorsal view. Trichobothria on posterior angles. Disc with very sparse and small punctures; lateral sides with dense, large and partly confluent punctures; interspaces with sparse and fine punctures. Scutellum rounded at apex, slightly wider than long.

Elytra. Lateral sides slightly widened posteriorly and widest at posterior 1/3, thence rounded at apex. Humeral calli well developed. Disc with 11 regular rows of large punctures, including a short scutellar row; several additional punctures between rows; interspaces with sparse and fine punctures. Epipleura impunctate, wholly visible in lateral view. Hind wing well developed.

Venter. Hypomera rugose with dense and coarse punctures on anterior 1/2. Prosternum with dense and coarse punctures bearing long setae; prosternal process weakly rugose, enlarged apically, bordered laterally, with sparse punctures. Metasternum with sparse and small punctures medially, moderately dense and large punctures laterally. Abdominal sternites with sparse to moderately dense punctures bearing short setae.

Legs. Moderately robust. Tibiae widened apically with a weakly developed preapical tooth. Fore legs with tarsomere 1 enlarged, very slightly narrower than 3 in male, weakly enlarged, slightly narrower than 3 in female. Tarsal claws appendiculate.

Genitalia. Aedeagus ( Fig. 9 ) very long and thin, with apical process swollen apically in dorsal view; straight, gradually narrowed, curved at apex in lateral view. Spermatheca absent.

Remarks. Four larvae were found in the abdomen of one female ( Fig. 11 ). Larvae have a well-developed head, many long setae on small tubercles, egg bursters and sclerotized tarsi. Ovoviviparity is rather common in Gonioctena and females tend to lose spermatheca ( Bontems 1988). This new species is also ovoviviparous and lacks a spermatheca.

Etymology. The specific name is derived from the Latin adjective metallica , referring to the metallic colour of head and pronotum.

Distribution. China (Sichuan).

Figures

FIGURE 11. First instar larvae of Gonioctena metallica sp. n.

FIGURES 1 – 4. Dorsal habitus (1 – 2) and head and pronotum (3 – 4). 1, 3. Gonioctena sichuana sp. n.; 2, 4. Gonioctena metallica sp. n. Scale bars = 1.0 mm.

FIGURES 5 – 10. Antenna (5, 8) and aedeagus (6 – 7, 9 – 10, dorsal and lateral views). 5 – 6. Gonioctena sichuana sp. n.; 7. Gonioctena coreana; 8 – 9. Gonioctena metallica sp. n.; 10. Gonioctena yunnana. Scale bars = 1.0 mm.