Gastrocentrum dux (Westwood, 1852)

Yang, Ganyan, Yang, Xingke & Shi, Hongliang, 2020, Taxonomy and phylogeny of the genus Gastrocentrum Gorham (Coleoptera, Cleridae, Tillinae), with the description of five new species, ZooKeys 979, pp. 99-132 : 99

Gastrocentrum dux (Westwood, 1852) Figures 2 , 10B , 14D , 25

Tillus dux Westwood, 1852: 46, pl. 24, f. 11 (type locality: "Nova Hollandia apud Fluvium Cygnorum", = Australia, Swan River); Blackburn, 1900: 119 ( Tillus ); Gahan, 1910: 61 ( Gastrocentrum ); Corporaal, 1950: 55 (catalogue; "Ceylon, India, Laos, Java?, Australia??"); Mawdsley, 1999: 270 (Sri Lanka).

Specimens examined.

Australia: " Tillus dux / australie / Museum Paris, Coll. A. Sicard 1930 / Gastrocentrum dux (Westwood, 1852), Det. Yang G. Y. 2013" (MNHN, 1 female, dissected; Fig. 2 ).

Diagnosis.

The specimen examined can be separated with G. magnum by elytral asetiferous punctations stop by apical fifth, not continuing to the tip (Fig. 10B ), intercoxal process of first abdominal ventrite not grooved, female pygidium with a semi-circle membranous region proximally, reaching half length of pygidium, lateral tail of spermathecal gland much shorter, only slightly longer than spermatheca (Fig. 14D , spglt).

Description.

General appearance: length 23-29 mm, robust, dark brown. Head: including eyes feebly broader than pronotum; eyes moderately large, distance between eyes nearly as long as the transverse diameter of eye; gular suture slightly convergent in anterior; antennae expanded laterally from 7th antennomere onwards; vertex and frons densely punctate, with a very faint ridge along midline, postgenae rugose. Pronotum: oblong, length/width ratio ca. 1.4, constricted posteriorly; surface finely and densely punctate, clothed with light yellow hairs. Elytra: oblong, sides subparallel, length/width ratio ca. 2.31, vested with light yellow setae; wedge-shaped protuberance present on inner surface; PAP in ten rows, AAP on interspaces between 1st-2nd, 3rd-4th, and 5th-6thPAP rows; AAP present in two very incomplete rows, number of AAP less than that in G. magnum ; AAP faintly smaller than PAP; interspace between 2nd-3rdPAP rows greater than punctation diameter; elytral punctations decreasing in size postmedially, and completely vanished at apical fifth (Fig. 10B ). Legs: outer apex of protibia very faintly extending outwards, not forming a distinct tooth. Abdomen: intercoxal process of the first ventrite flat, not grooved. Male genitalia: not studied. Female reproductive organs: pygidium slightly wider than long, posterior margin rounded, a semi-circle membranous region present proximally, reaching to half length of the pygidium; sixth ventrite trapezoidal, wider than long; bursa copulatrix clearly defined; spermathecal gland only with one lateral tail, which slightly longer than spermatheca in fully stretched condition (Fig. 14D , spglt); spermatheca boot-shaped (Fig. 14D , sp).

Note on type specimen.

Mawdsley (1999) claimed that the type specimen of G. dux was deposited in the Hope Department of Entomology, University Museum, Oxford, United Kingdom, but it was not located during a visit to that museum in 2011 by the first author. Westwood (1852) indicated that the type specimen was from "Mus. Melly", but efforts to locate it in Melly’s collection in the Natural History Museum, Geneva, yielded no results either. The whereabouts of the type specimen remains unknown.

Discussion.

The Australian type locality of this species is doubted by the Australian entomologist and clerid worker Justin Bartlett who, after viewing the Cleridae holdings of all major museum, and several agricultural and private collections from all Australian states, is yet to find a single Gastrocentrum specimen, and therefore does not believe G. dux to be an Australian species. He also doubts that the locality label of the specimen examined in this manuscript represents an actual collecting event, but rather was labelled after it was identified as G. dux , with the associated type locality of ‘Australie’ (pers. comm. J Bartlett). He also pointed out that another apparently Australian specimen from Melly’s collection, a longicorn Hephaestion acraetus Newman, is in fact a Chilean species (see Saunders 1850), providing a precedent for erroneously labelled specimens from Melly’s collection. Despite this, no more practical specimen-based evidence for or against this argument has been found. Hence, we can only describe this species based on the specimen mentioned above at the moment, as we can only take the label at face value and assume it to represent an actual collecting label.

We found a Tenebrionidae beetle with the same Swan River type locality also originating from Melly’s collection and described by Westwood: Prophanes aculeatus Westwood, 1849. It is presently treated as a valid species, with an eastern, not western, Australian distribution ( Westwood 1849; Carter 1913; Matthews 1992). Gastrocentrum dux may have a similar historical story and its correct occurrence could be in other areas of Australia or in other regions of the world, but this hypothesis needs to be proved by further specimens.

Figures

Figure 10. Drawing of elytral asetiferous punctations. A Gastrocentrum magnum sp. nov. B G. dux C G. regulare sp. nov. D G. xiaodongi sp. nov. E G. gaoligongense sp. nov. F-H G. zayuense sp. nov. The numbers 1 - 10 annotate the serial rows of primary asetiferous punctuations (PAP). Abbreviations: a accessory asetiferous punctations.

Figure 14. A-C Gastrocentrum magnum sp. nov. female, paratype from Assam A pygidium B sixth ventrite C female reproductive organ D Gastrocentrum dux from Australia, female reproductive organ. Abbreviations: ali alimentary canal bc bursa copulatrix cov common oviduct olb oblique bacculi ovp ovipositor sp spermatheca spg spermathecal gland spgtt top tail of spermathecal gland spglt lateral tail of spermathecal gland va vagina vtb ventral bacculi. Scale bar: 1 mm.

Figure 25. Geographical distribution map of the genus Gastrocentrum.

Figures 1 - 9. Habitus. 1 Gastrocentrum magnum sp. nov. Holotype 2 G. dux from Australia 3 G. unicolor (Lectotype of G. pauper) 4 G. regulare sp. nov. Holotype 5 G. xiaodongi sp. nov. Holotype 6 G. zayuense sp. nov. Holotype 7 G. gaoligongense sp. nov. Holotype 8 Tillus nitidus comb. nov. Holotype 9 Isocymatodera atricolor Syntype. Scale bars: 5 mm (1, 2) 2 mm (3 - 9).