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938


Journal of Paleontology 91(5):933–959


Bergeron’s line drawing was based (Bergeron, 1899, fig. 9) as the lectotype of the species because it was the only illustration Bergeron published of A. chauveaui. As originally published (Bergeron 1899, fig. 9; reproduced herein as Fig. 2.1), the exoskeleton was separated into three parts—cranidium, thorax, and pygidium—but examination of the limestone slab makes it clear that the illustration is of an exoskeleton separated into a thoracopygon with an associated, inverted cranidium (Fig. 2.2, 2.3). Bergeron’s (1899) description also seems to apply to this specimen. Because the individual specimen on which most of Bergeron’s (1899) original published information was based can be identified from the original slab of examined material, there can be little doubt that it was the intended ‘type,’ and by implication should be the lectotype of the species. Lane et al. (1988) seem to have followed this line of


reasoning, but a mixup evidently occurred at publication stage, leading to designation of an inverted cranidium, E.M. 90001b (Fig. 2.5, 2.6) as the lectotype of Arthricocephalus chauveaui. That specimen is here reassigned to Oryctocarella duyunensis (Qian, 1961). The article by Lane et al. (1988) was published in Chinese and English, and the Chinese portion of the paper was translated from a draft originally written in English. In the English description, Lane et al. (1988) clearly referred to the exoskeleton (E.M. 90001a) rather than the cranidium (E.M. 90001b) as the specimen selected to be the lectotype. As described (Lane et al., 1988, p. 559), the cranidium has a “subrectangular glabella” (not a cylindrical glabella as present in E.M. 90001b) and “four pairs of deep glabellar pits, S1–S3 reaching to axial furrows and connected across glabella also connected across glabella by shallow transverse furrow” (not isolated from the axial furrows); the thorax has “pleurae with weak as geniculation” (i.e., segments are fulcrate rather than non-fulcrate, implying the presence of thoracic facets). As discussed above, the only exoskeleton in Bergeron’s (1899) suite of examined specimens that meets all these criteria is E.M. 90001a. In the Chinese translation, the discussion related to the


designation of the specimen in Bergeron’s (1899) figure 9 as the lectotype, and the description of the glabellar furrows meeting the axial furrows, were omitted. According to P.D. Lane (written communication, 2016), designation of a lectotype was somehow changed from that in the draft, without his knowledge, both in the description and plate explanation. As published, a cranidium, E.M. 90001b, was indicated as the lectotype (Lane et al., 1988, p. 555, 558, 559, pl. 1, right in fig. 2; herein, Figs. 1.5, 2.5, 2.6). The Chinese part of the article was published prior to the English portion, and the altered designation of lec- totype, which was at odds with the written morphological description published later in English, was included in it. Repetition of this designation at the time when the English portion of the article was published exacerbated the problem. Because the cranidium (E.M. 90001b) was erroneously


selected as the lectotype of Arthricocephalus chauveaui, but in fact belongs to Oryctocarella duyunensis, it has been the source of some misinterpretation of the concepts of both Arthricocephalus and A. chauveaui. Blaker and Peel (1997, p. 110, fig. 62.1) and Geyer (2005, fig. 3) interpreted the largest exoskeleton on Bergeron’s (1899) slab (E.M. 90001a) as the basis for Bergeron’s (1899) illustration, indicating it as the


lectotype of the species, and discussed the concept ofA. chauveaui in light of that view. M.R. Blaker was a co-author of the Lane et al. (1988) paper, and his 1997 monograph (Blaker and Peel, 1997) showed that he did not realize there had been a change in the designation of a lectotype for A. chauveaui. Yuan et al. (2002, p. 120) and McNamara et al. (2003,


p. 107) accepted the cranidium (E.M. 90001b) with its asso- ciated thoracopygon (E.M. 90001c) to be the lectotype and discussed a different concept of Arthricocephalus chauveaui. The cranidium and its associated thoracopygon may originate from a single individual, but Lane et al. (1988, p. 555, 559) definitely specified the cranidium to be the lectotype. This thoracopygon differs considerably from the thorax and pygi- dium illustrated by Bergeron (1899, fig. 9; = E.M. 90001a). The differences from Bergeron’s illustrated specimen include a greater number of thoracic segments, non-fulcrate segments, and a pygidium that is shorter and less segmented. The species concept discussed by Yuan et al. (2002, p. 120) and McNamara et al. (2003, p. 107) applies to Oryctocarella duyunensis. We conclude that the designation of the crandium (E.M.


90001b) from Bergeron’s (1899) limestone slab by Lane et al. (1988) is invalid. As discussed above, Bergeron’s original illustration (1899, fig. 9) allows us to infer that E.M. 90001a was the intended ‘type,’ deemed a lectotype, of A. chauveaui despite the fact that Bergeron (1899) obviously regarded all specimens on the slab as belonging to the same species. According to Article 74.1.3 of the Zoological Code (ICZN, 1999), “The valid designation of a lectotype permanently deprives all other spe- cimens that were formerly syntypes of that nominal taxon of the status of syntype.” Because the intended ‘type’ can be unequi- vocally identified from the syntypic series through comparison to the original illustration (Bergeron, 1899, fig. 9), subsequent designation of any other specimen as a lectotype would be invalid and misleading. Furthermore, in accordance with Recommendation 74B of the Code (ICZN, 1999), “Other things being equal, an author who designates a lectotype should give preference to a syntype of which an illustration has been pub- lished.” Bergeron’s illustration (1899, fig. 9) was evidently based on a single specimen, E.M. 90001a, and this specimen therefore should have priority for designation as a lectotype over any non-illustrated sclerite in the original syntypic series.


Historical review of Arthricocephalus and its junior synonyms


Saito (1934, p. 232, pl. 25, figs. 26–29) questionably referred some specimens from northwestern Korea to Arthricocephalus. According to Rasetti (1959, p. O220) and Blaker and Peel (1997, p. 109), these specimens do not belong to Arthricocephalus but to Cheiruroides Kobayashi, 1935. Rasetti (1959, p. O524) regarded the genus Arthricocephalus to be unrecognizable and therefore failed to include it in the family Oryctocephalidae. Qian (1961) assigned some specimens from the Balang


Formation at Palang, Duyun, southeastern Guizhou, China, to a new species of Arthricocephalus, A. duyunensis. Qian’s (1961) material is from a locality ~100km southwest of Tongren, the type locality of A. chauveaui. As revised here, these specimens


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