Sinodrepanus rex
Creators: name: Montanaro, Giulio
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Sinodrepanus
Sinodrepanus rex

description: Sinodrepanus rex (Boucomont, 1912)
(Figs. 3g –h)
Drepanocerus rex Boucomont, 1912: 277 (original description); Janssens, 1953: 25
Drepanocerus arrowi Balthasar, 1932 (original description): 64; Janssens, 1953: 37 (as synonym of S. rex)
Sinodrepanus rex: Simonis, 1985: 98; Krikken, 2009: 21; Bai et al., 2011: 10; Kabakov & Shokhin, 2014: 57; Bai et al., 2017: 42; Li et al., 2018: 416; Bezdĕk, 2016: 174; Bezděk & Krell, 2006: 157
Sinodrepanus arrowi: Simonis, 1985: 96 (as putative synonym of S. rex); Krikken, 2009: 21 (as putatively valid species); Kabakov & Shokhin, 2014: 57 (as synonym of S. rex); Roggero et al., 2015: 154, 156, 174; Bezdĕk, 2016: 174 (as synonym of S. rex); Bezděk & Krell, 2006: 157 (as synonym of S. rex)
Type locality: Yunnan.
Type material examined. Drepanocerus rex. Syntype no. 1, ♂ (MNHN): Yunnan [wc, pb] // MUSÉUM PARIS / [1?]936 / COLL. A. BOUCOMONT [wc, pb] // ♂ [wc, pb] // A. Janssens vid., 1953 / Drepanocerus / rex ♂ / Boucomont / Type [wc, hb except “A. Janssens” and “., 195” pb] // Typus [rc, pb] // SYNTYPE [rc, pb] // SYNTYPE / Sinodrepanus / rex (Boucomont) [wc, pb] // MNHN / EC8105 [wc, pb]. Syntype no. 2, ♂ (MNHN): Yunnan [wc, pb] // MUSÉUM PARIS / [1?]936 / COLL. A. BOUCOMONT [wc, pb] // Typus [rc, pb] // SYNTYPE [rc, pb] // SYNTYPE / Sinodrepanus / rex (Boucomont) [wc, pb] // MNHN / EC8106 [wc, pb].
Drepanocerus arrowi. Lectotype (by present designation), ♂ (NMPC) (Fig. 3g –h): Giufu-Shan / Szechuan / Em. Reitter [wc, pb] // Typus [rc, hw] // Det. Dr. Balthasar / D. Arrowi m. [wc, line 1 pb, line 2 hb] // 249 / ♂ / BPR [wc, hb] // ex. coll. V. Balthasar / National Museum / Prague, Czech Republic [wc, pb] // LECTOTYPE / Drepanocerus arrowi / Balthasar, 1932 / G. Montanaro des. 2023 [rc, hb; dissected genitalia are mounted on a separate microscope slide marked with “249”, preserved in the same box of the lectotype]. Paralectotype no. 1, ♀ (NMPC): Giufu-Shan / Szechuan / Em. Reitter // Typus // Det. Dr. Balthasar / D. Arrowi m. // ex coll. V. Balthasar / National Museum / Prague, Czech Republic // Drepanocerus / arrowi / Balth. Paralectotype no. 2, ♀ (NMPC): Typus // Giufu-Shan / Szechuan / Em. Reitter // Det. Dr. Balthasar / D. Arrowi m. // ex coll. V. Balthasar / National Museum / Prague, Czech Republic. Paralectotype no. 3, ♂ (NMPC): Typus // Giufu-Shan / Szechuan / Em. Reitter // Det. Dr. Balthasar / D. Arrowi m. // ex coll. V. Balthasar / National Museum / Prague, Czech Republic [the head is missing]. Paralectotype no. 4, ♂ (NMPC): Typus // Giufu-Shan / Szechuan / Em. Reitter // Typus // Det. Dr. Balthasar / D. Arrowi m. // 248 / ♂ / BPR // ex coll. V. Balthasar / National Museum / Prague, Czech Republic. Paralectotype no. 5, ♂ (BMNH): Co- / type [wc, pb, circled in yellow] // Typus [rc, hb] // Giufu-Shan / Szechuan / Em. Reitter [wc, pb] // BMNH (E) / 1237594 [wc, pb; genitalia mounted on a cardboard pinned with the specimen].
Additional material examined (1♂, 1♀). China: Giufu-Shan, Szechuan, Em. Reitter [1♀, NMPC; found within the series of D. arrowi syntypes but not labeled as a syntype]; Thibet, Tse Kou, 1902, R. P. J. Dubernard legit [1♂, JSCS].
Diagnosis. Sinodrepanus rex shares with S. besucheti, S. rosannae Simonis, 1985, S. thailandicus and S. tsaii the presence of delimited tufts of setae on interstria 5. Major males can be separated from males of S. besucheti and S. tsaii due to the narrowly protruding clypeus (truncated medially in the other species), and from S. thailandicus by the wider, rectangular-shaped (not rounded laterally) tip of the medial clypeal tooth. However, the examination of male genitalia remains the most effective way to get a sure identification, with the most apparent character being the strong tooth on the superior right branch of the lamella copulatrix (Simonis 1985), much less developed in all other species. Compared to S. thailandicus, the basolateral plate of paramere is well developed, almost reaching the posterior edge of parameral apex in lateral view (ending clearly before the parameral apex in S. thailandicus). Sinodrepanus rosannae has clearly shorter parameres, with basolateral plate overlapping with parameral apex in lateral view. See also the identification key below. Females can be distinguished from those of S. rosannae by the protibiae with 4 teeth (3 in S. rosannae), but the association with males is required to reasonably exclude the remaining taxa.
Distribution. China (Boucomont 1912; Balthasar 1932, 1963; Kabakov & Shokhin 2014; Li et al. 2018). Balthasar (1963) recorded this species from Vietnam (as S. arrowi); however, this record should be considered as doubtful due to the proven confusion made by the Czech author between S. arrowi and S. besucheti (see below).
Etymology. Rex is a Latin noun meaning “king”.
Remarks. Drepanocerus arrowi was described by Balthasar (1932) on a series of specimens from Giufu-Shan, currently known as Jinfo Shan in the Chinese municipality of Chongqing (Bezděk et al. 2015). In his description, the author stated that the species is very close to Drepanocerus rex Boucomont, 1912 and provided an identification table to separate the two species. However, Balthasar had never seen D. rex and his diagnosis was based solely on Boucomont’s (1912, 1921) descriptions.
Later, Janssens (1953) compared the type of S. rex and two syntypes of S. arrowi, and concluded that the two names refer to the same species. One of the most striking differences advocated by Balthasar (1932) to differentiate the two taxa was the length of the first metatarsomere: as long as the second and third metatarsomeres together in S. rex (according to Boucomont’s (1912) description), and as long as tarsomeres 2–5 in S. arrowi. However, both species actually present the latter character state, and—as Janssens (1953) noticed—the one given by Boucomont (1912) appears to be only due to a lapsus. Additionally, Balthasar (1932) misinterpreted sexual dimorphism in his new species. In S. rex, major males have the anterior margin of clypeus strongly produced, subtrapezoidal and upturned; in minor males the clypeus is only slightly upturned and notched medially; in females, the clypeus has two strong teeth. As clearly shown by its drawings, Balthasar (1932: 66) interpreted actual major males as females, and minor males and females as males of his S. arrowi. This mistake was later corrected by the Czech author himself (Balthasar 1963).
Nevertheless, Balthasar (1963) denied Janssens’ (1953) synonymy. He argued that Boucomont’s description of S. rex was inconsistent with the type of such species and proposed two interpretations (Balthasar 1963: 65, lines 25–30): 1) the type of S. rex preserved at MNHN and examined by Janssens (1953) was not the actual specimen studied by Boucomont. Therefore, the “false” holotype, which Balthasar implicitly recognized as being conspecific with S. arrowi (!), should not have been considered a type specimen; 2) Boucomont’s description, if truly referring to the type in MNHN, should be considered a “ descriptio falsa ” given its great imprecision, and S. rex should be treated as a nomen nudum. Relying on these two objections, Balthasar (1963) kept his S. arrowi as the only valid taxon name for the species currently recognized as S. rex.
Later on, Simonis (1985) came to the same conclusions of Janssens (1953) after examining a syntype of S. arrowi. However, since he was not able to study the full type series of Balthasar’s species, Simonis (1985) refrained from formally confirming the synonymy. Moreover, he examined a non-type specimen identified as S. arrowi by Balthasar himself, which in fact belonged to another species, S. besucheti Simonis, 1985. I have found myself a series of specimens of S. besucheti preserved in NMPC, most likely seen by Balthasar and put together with specimens of S. rex. Due to the confusion of Balthasar between the two species just mentioned, the record of S. arrowi from Northern Vietnam (“ Tonkin ”) by Balthasar (1963) would benefit of a confirmation.
Subsequent authors (Kabakov & Shokhin 2014; Bezdĕk & Krell 2006; Bezdĕk & Hájek 2012; Bezdĕk 2016; Li et al. 2018) mostly considered the two names as synonyms with S. rex having priority, except for Krikken (2009), who considered the matter still unresolved, and Roggero et al. (2015), who apparently considered S. arrowi a good species.
I studied all syntypes of S. arrowi preserved in Balthasar’s collection (now in NMPC), as well as a syntype preserved at BMNH. My conclusions are in agreement with those of Janssens (1953) and Simonis (1985) in that, without doubt, S. arrowi is a junior subjective synonym of S. rex. The nomenclatural objections advocated by Balthasar (1963) to justify the priority of the name S. arrowi against that of S. rex must be considered invalid. Indeed, there is no evidence that the specimen currently considered the holotype of S. rex is not the one meant by Boucomont (1912). Also, the mistakes in Boucomont’s description are not sufficient to claim the invalidation of the taxon name (A. Ballerio, personal communication). So, Sinodrepanus rex is the current valid name to be applied to our species.
To stabilize nomenclature, I designate a medium sized male preserved at NMPC as lectotype of S. arrowi. Apparently, the syntypes are all conspecific. The only atypical thing I noticed is that one of them, a small male, has only three teeth on the outer protibial margin—the apical fourth teeth, usually found in the species, is missing. This could just be due to variation or wear, since all other characters (including the highly diagnostic genitalia) correspond to those of S. rex.
description: Published as part of Montanaro, Giulio, 2024, New or poorly known species of Sinodrepanus Simonis, 1985 (Coleoptera: Scarabaeidae: Oniticellini), with the first identification key for the genus, pp. 577-595 in Zootaxa 5537 (4) on pages 582-587, DOI: 10.11646/zootaxa.5537.4.10, http://zenodo.org/record/14240160