Gonioctena (Sinomela) nigroplagiata Baly, 1862

Lee, Chi-Feng & Hsieh, Chia-Hung, 2022, Integrative taxonomy of the leaf-beetle genus Gonioctena Chevrolat, 1836 in Taiwan (Coleoptera, Chrysomelidae, Chrysomelinae, Gonioctenini) reveals new synonymies and one new species, ZooKeys 1120, pp. 1-46 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.1120.87526
publication LSID	lsid:zoobank.org:pub:711E0A82-82AB-43B5-9CC4-89BD87955061
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scientific name	Gonioctena (Sinomela) nigroplagiata Baly, 1862
status

Treatment

Figs 17 View Figure 17 , 18 View Figure 18 , 19 View Figure 19

Gonioctena nigroplagata [sic!] Baly, 1862: 28 (Japan).

Phytodecta nigroplagiata : Jacoby 1885: 210 (catalogue).

Phytodecta (s. str.) nigroplagiatus : Weise 1916: 178 (catalogue).

Phytodecta nigroplagiatus : Winkler 1930: 1296 (catalogue); Chen 1934: 74 (China).

Phytodecta (Sinomela) nigroplagiatus : Chen 1935: 129 (catalogue); Chen 1936: 87 (catalogue).

Gonioctena (Sinomela) nigroplagiatus : Chûjô and Kimoto 1961 (catalogue).

Gonioctena (Sinomela) nigroplagiata : Gressitt and Kimoto 1963: 366 (catalogue); Kimoto 1964: 280 (catalogue); Takizawa 1976: 464 (larva); Takizawa 2007: 45 (aedeagus and color polymorphism); Kippenberg 2010: 436 (catalogue); Yang et al. 2015: 55 (catalogue); Cho 2016: 294 (redescription).

Phytodecta robusta Jacoby, 1885: 209 (Japan); synonymized by Chûjô and Kimoto (1961). Synonym confirmed.

Phytodecta (s. str.) robustus : Weise 1916: 181 (catalogue).

Phytodecta robustus : Winkler 1930: 1296 (catalogue).

Phytodecta (Sinomela) nigroplagiatus var. robustus : Chen 1935: 129 (catalogue); Chen 1936: 87 (catalogue).

Types.

Gonioctena nigroplagiata . Lectotype ♀ (here designated to clarify identity relative to G. robusta , NMHUK): "Type [h, w] // Type / H. T. [p, w, circle card with red border] // Baly Coll. [p, w] // Gonioctena / Gonioctena nigroplagiata / Baly / Japan [p, b] // Gonioctena / ( Sinomela ) / Gonioctena nigroplagiata / (Baly) [h] / Det. S. GE 2004 [p, w]". Paralectotype: 1♀ (NMHUK): "Type [h, w] // Baly Coll. [p, w] // SYN- / TYPE [p, w, circle card with blue border]".

Phytodecta robusta . Lectotype ♂ (Here designated for to clarify identity relative to G. nigroplagiata , NMHUK): "Japan / Lewis [h, w] // SYN- / TYPE [p, w, circle card with blue border] // Jacoby Coll. / 1909-28a. [p, w] // Gonioctena robusta Jac [h, b]". Paralectotype: 1♀ (TARI): "Hiogo / JAPAN / 8.VI.1881 / Col. G. Lewis [h, w] // CO / Type [p, w, circle card with yellow letters and border] // Phytodecta / Phytodecta robustus / Jacoby [h] / DET. M. CHUJO [p, w] // Phytodecta / Phytodecta robusta Jac [h] / Det. T. Shiraki [p, w] // 1636 [p, w]".

Other material (n = 95).

Taiwan. Matsu islands: 17♂, 17♀ (TARI), Nangan (南竿), 7.VI.2017, leg. T.-C. Chen ; 23♂, 35♀ (TARI), same locality, 8.VI.2017, leg. Y.-L. Liu ; 1♀ (TARI), same locality, 28.VI.2017, leg. H.-T. Fang ; 1♂, 1♀ (TARI), Beigan (北竿), 18.IV.2020 , C.-H. Tsieh.

Redescription.

Length 6.1-7.3 mm, width 3.8-4.7 mm. Body color (Fig. 17G-I View Figure 17 ) yellowish brown; scutellum black; elytra with three pairs of black spots arranged as follows: posterior pair largest at apical 1/3, transverse, from near suture to near lateral margins, extending posteriorly near lateral margins; two pairs of black spots near basal margin, one oval to oblong pair near suture, the other on humeral calli, triangular, anteriorly narrowed. Meso- and metathorcic and abdominal ventrites darker. Antennae (Fig. 18A View Figure 18 ) with antennomere III-IV slender, V-VI slightly swollen, VII-X moderately swollen, XI elongate oval, length ratios of antennomeres I-XI 1.0: 0.6: 0.6: 0.6: 0.3: 0.5: 0.5: 0.5: 0.5: 0.5: 0.9, length to width ratios of antennomeres I-XI 2.2: 1.9: 2.7: 2.1: 1.0: 1.5: 1.5: 1.4: 1.3: 1.1: 2.0. Pronotum 2.3-2.4 × wider than long, lateral margins widest at base, convergent anteriorly, anterior angles strongly produced; anterior and lateral margins bordered, lateral margins barely visible in dorsal view; trichobothria present on anterior and posterior angles; disc covered with sparse fine punctures and mixed with finer punctures; both sides covered with much larger, denser punctures. Scutellum distinctly wider than long, narrowed posteriorly. Elytra 1.1 × longer than wide; lateral margins slightly wider posteriorly, widest near middle, convergent posteriorly; humeral calli well developed; disc covered with regular coarse punctures arranged into single stria; interspaces covered with fine, sparse punctures. Hind wing well developed. Aedeagus (Fig. 18B, C View Figure 18 ) with apical margin widely rounded and medially notched, anterior angles acutely hooked, lateral margins slightly narrowed at basal 1/3; moderately curved in lateral view; endophallic sclerite short, apex narrowly rounded in dorsal view, acute process in lateral view. Gonocoxae (Fig. 18D View Figure 18 ) wide, apical margins irregular, with dense long setae along apical margins. Ventrite VIII (Fig. 18E View Figure 18 ) transverse and membranous, with dense long setae along outer margin. Spermatheca reduced.

Variations.

Black areas on dorsum and venter are reduced to different degrees in various individuals. Some adults have smaller black spots arranged into four pairs on the elytra, with only the central part of the scutellum blackish brown, and only the meso- and metathoracic ventrites darker (Fig. 17D-F View Figure 17 ). Pale adults have entirely yellowish brown bodies (Fig. 17A-C View Figure 17 ).

Diagnosis.

Gonioctena (Sinomela) nigroplagiata is easily separated from the other consubgeneric species, G. (S.) osawai by the following combination of the characters: no black spots on the dorsum, none or three or four pairs of black spots on the elytra (Figs 17 View Figure 17 ) (one pair of black spots on pronotum and five pairs of black spots on elytra in G. (S.) osawai (Fig. 14G View Figure 14 ); wide antennomere V, width subequal to length (Fig. 18A View Figure 18 ) (elongate antennomere V, more than 2.0 × longer than wide in G. (S.) osawai (Fig. 20A View Figure 20 )); narrowly rounded apex of endophallic sclerites (Fig. 18B View Figure 18 ) (bifurcate and asymmetrical apices of endophallic sclerites in G. (S.) osawai (Fig. 20B View Figure 20 )); wide gonocoxae covered with more setae (Fig. 18D View Figure 18 ) (narrow gonocoxae covered with fewer setae in G. (S.) osawai (Fig. 20D View Figure 20 )); membranous ventrite VII with dense setae along apical margin (Fig. 18E View Figure 18 ) (slightly sclerotized ventrites VIII with dense setae only on apices in G. (S.) osawai (Fig. 20E View Figure 20 )).

Host plants.

Cannabaceae : Celtis sinensis Pers. ( Chûjô and Kimoto 1961; present study) (Fig. 19A View Figure 19 ).

Biology.

A mass outbreak of adults of this species occurred on Matsu Islands during June 2017. The large numbers of beetles made local citizens nervous and made the news. A number of specimens were sent to the authors for identification. Mr. Hua-Te Fang (方華德) collected larvae (Fig. 19B View Figure 19 ) on 15 April 2021 at the locality. Mature larvae burrowed into soil and built underground chambers for pupation (Fig. 19C View Figure 19 ) on 22 April. The first adults emerged from soil on 2 May and were entirely yellowish brown (Fig. 19D View Figure 19 ). Black spots appeared after three days in some individuals and become stable within five days (Fig. 19E, F View Figure 19 ). No adults were observed in the field by Mr. Fang on 11 May, 29 September, and 21 October. This species is presumed to be univoltine, and larvae are active only during spring.

Remarks.

The original spelling in the original description ( Baly 1862) is incorrectly printed as " Gonioctena nigroplagata ". It is obviously a typographical error and the correct spelling is " Gonioctena nigroplagiata ".

Distribution.

China, Japan, Taiwan (only on Matsu Islands, including Beigan Island北竿島and Nangan Island 南竿島).