Gastrocentrum Gorham, 1876

Bartlett, Justin S., 2023, Clarification of ambiguous genus records for Australian Cleridae (Coleoptera: Cleroidea), Zootaxa 5383 (3), pp. 375-382 : 377-379

Genus Gastrocentrum Gorham

Gastrocentrum dux (Westwood) : Westwood (1853) described Tillus dux from “Nova Hollandia apud Fluvium Cygnorum”, i.e., New Holland near Swan River, from material “In Mus[eum] Melly” and stated to be 13 and-a-half ‘lines’ in length, i.e., approx. 3 cm. Blackburn (1900) referred to Tillus dux as a “complete enigma” and, due to its large size, considered it likely to represent a misidentified species of Natalis (now Eunatalis ). Schenkling (1903: 13) indicated doubt about the Australian distribution of Tillus dux and, in a subsequent catalogue ( Schenkling 1910: 25) listing it as Gastrocentrum dux following Gahan (1910), mentioned only Ceylon and Java, omitting Australia altogether from its distribution. Corporaal (1950a) clearly expressed doubt over the validity of the Australian type locality, giving the distribution of G. dux as “ Ceylon, India, Laos, Java (?), Australia (??)”. Gerstmeier (2005), adding Thailand and Burma to the known distribution of G. dux , reiterated Corporaal’s doubt about its occurrence in Australia. Mawdsley (1999), however, focusing only on the Sri Lankan fauna, offered no comment on the type locality of G. dux . After 20 years of researching clerids, including documenting the Cleridae collections of 16 Australian and six European institutional collections (see Table 1 ), plus several private collections, this author has not found a single Gastrocentrum specimen undeniably collected in Australia.

Yang et al. (2020) recognised nine species, five newly described, in their revision of Gastrocentrum which omitted Gastrocentrum brevicolle (Pic) due to unavailability of specimens. Of the three remaining already described species, type material was studied for G. unicolor (White) and G. laterimaculatum Gerstmeier , but not for G. dux (Westwood) . Their interpretation of G. dux was therefore based on a single Gastrocentrum specimen bequeathed to the MNHN, Paris in 1930 from the collection of French Coleopterist Albert Sicard, labelled “ Tillus dux ” and, on a separate label, “ Australie ”, which cannot simply be assumed to represent the place of collection... particularly when: a) the fact that it is printed in the same hand, on the same blue coloured paper and seemingly using the same ink (see Yang et al. 2020: fig. 2) as the “ Tillus dux ” label suggests high likelihood that both labels were printed, and added to the specimen, at the same time, the “ Australie ” label potentially based on the published type locality of the species the specimen was at that time determined to be, rather than necessarily indicating a collecting locality; b) the historical precedent for considering the Australian type locality of T. dux erroneous is well-established in the published literature (see above); and, c) the genus Gastrocentrum is not represented by a single Australian-collected specimen in any Australian institutional or private collection (also see above).

Additionally, in support of point ‘b’, it is known that individual specimens within the Melly Collection (in the Muséum d’histoire naturelle de Genève, Switzerland), commonly do not have locality and identification labels attached to them, with locality data only loosely associated with specimens by their position above a ‘taxon name & region’ label within drawers ( Guéorguiev et al. 2014). Several instances of doubt or confusion around collecting data of Melly material have been reported in the taxonomic literature (e.g., Saunders 1850, Kuijten 1983, Flores & Pizarro-Araya 2010), and I have likewise found numerous examples of Melly Collection material completely lacking locality data (e.g., Kuijten 1983, Geiser 2010, Sandoval-Gómez et al. 2014, Pecci-Maddalena & Lopes-Andrade 2017, Seidel et al. 2018).

In his description of Tillus dux, Westwood (1853) writes of the insect in general as “ fusco-nigricans, setosus, pubescentia aurea obstus ” (i.e., brown-black, bristly, covered with golden pubescence), of the prothorax as “ elongatus, subcylindricus, elytris multo angustior, antice parum latior, ante et pone medium puallo constrictus ” (i.e., elongate, subcylindrical, much narrower than the elytra, a little wider anteriorly, constricted in front and at the middle by a pustule) and of the elytra as “ nubila seu fascia indistincta ante medium obscura ” which translates to “a dark cloud or indistinct band before the middle” with the latter feature suggestive of interruption in the distribution of the golden setae. The illustration of T. dux published by Westwood (1853; plate 24, fig. 11) clearly shows a dark section of the elytral disc positioned above the middle, interrupting what appears to represent the more broadly distributed golden pubescence mentioned in the description. Of the described Gastrocentrum species only G. magnum Yang, Yang & Shi approaches G. dux in body size, and the high-resolution photograph of G. magnum ( Yang et al. 2020: Fig. 1 ) clearly shows elytra that are densely vested with golden setae, with a darker area above the middle where the setae are absent, exactly as described and illustrated by Westwood (1853). Additional points of consideration include: 1) the fact that G. dux determination labels are affixed to the pins of two G. magnum Paratypes from north-eastern India (Assam and Sikkim); and 2) much of the distribution given by Yang et al. (2020) for G. magnum ( India, China, Vietnam, Thailand) overlaps with the previously known distribution of G. dux .

Regarding the published type locality, “Nova Hollandia apud Fluvium Cygnorum”, i.e., New Holland near Swan River, there is, interestingly, a Swan River near the southern border of the State of Himachal Pradesh, in northern India. Geographically, just as Sikkim (where G. magnum occurs) does, Himachal Pradesh adjoins the southern Tibetan border. Considering the similarity between G. magnum Yang et al. and G. dux sensu Westwood (not sensu Yang et al.), and the possibility that the former is synonymous with the latter, it seems plausible to suggest that the western-most populations of such a sub-Himalayan-adapted species might extend as far as Himachal Pradesh from Sikkim. Himachal Pradesh is also only about 800 km northwest of the nearest known locality for the genus Gastrocentrum, Modi Khola , Nepal (for G. xiaodongi Yang et al. 2020 ).

In the absence of establishing morphological congruence between the abovementioned MNHN “ Australie ” specimen and Westwood’s Tillus dux syntype, the morphological concept of G. dux sensu Yang et al. (2020) is supported only by faith that the “ Australie ” label represents a collecting event; not a strong case for its occurrence in Australia compared to the evidence presented above to the contrary. Therefore, as, after 160 years since the description of Tillus dux , there remains no definitive specimen-based evidence for the occurrence of Gastrocentrum dux in Australia, I propose that the genus Gastrocentrum be considered absent from the Australian fauna and the Australian type locality of Tillus dux erroneous. The status of Gastrocentrum magnum Yang, Yang & Shi in relation to Gastrocentrum dux Westwood requires further consideration.

Distribution: Requires clarification, but potentially India, Sri Lanka, southern China, Laos, Thailand, Vietnam, Burma ( Corporaal 1950a, Mawdsley 1999, Gerstmeier 2005, Yang et al. 2020).

Status: Gastrocentrum dux is non-native and absent in Australia.

Figures

FIGURES 1–8. (1) Syntype specimen of Chalciclerus pantomelas Boisduval (MNHN); (2) specimen of Balcus violaceus (Fabricius) erroneously labelled as a type specimen of Chalciclerus pantomelas Boisduval (MNHN); (3) specimen of Thallis janthina Erichson (Erotylidae) (SDEI) misidentified by Sigmund Schenkling as Korynetes abdominalis (Fabricius); (4) syntype specimen of Corynetes unicolor Chevrolat, 1876 (MNHN), a synonym of Korynetes coeruleus (De Geer); (5) syntype specimen of Labasiella duboulayi Pic, 1950 (MNHN), a synonym of Solervicensia ovata (Spinola); (6) syntype specimen of Elasmocerus picticollis Blackburn, 1901 (NHML), a synonym of Monophylla terminata (Say).