Tanidromites, Schweitzer and Feldmann, 2008 a

Klompmaker, Adiël A., Starzyk, Natalia, Fraaije, René H. B. & Schweigert, Günter, 2020, Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura), Palaeontologia Electronica (a 32) 23 (2), pp. 1-54 : 28

Genus TANIDROMITES Schweitzer and Feldmann, 2008a

Type species. Prosopon insigne von Meyer, 1857 , by original designation.

Included species. Tanidromites aequilatus (von Meyer, 1857) , as Prosopon ; T. alexandrae Starzyk, 2015a ; T. etalloni (Collins in Collins and Wierzbowski, 1985), as Coelopus ; T. hyznyi (Starzyk, 2015b) , as Eodromites ; T. insignis (von Meyer, 1857) , as Prosopon ; T. lithuanicus Schweigert and Koppka, 2011 ; T. longinosa Starzyk, 2016 ; T. maerteni Fraaije, Van Bakel, Guinot, and Jagt, 2013 ; T. montreuilense Crônier and Boursicot, 2009 ; T. muelleri Krobicki and Zatoń, 2016 ; T. nightwishorum sp. nov.; T. pustulosa (von Meyer, 1860) , as Pithonoton ; T. raboeufi Robin, Van Bakel, d’Hondt, and Charbonnier, 2015 ; T. richardsoni (Woodward, 1907) , as Prosopon ; T. scheffnerae Schweigert and Koppka, 2011 (= T. wysokaensis Starzyk, 2016 ); T. sculpta (Quenstedt, 1858) , as Prosopon (= Prosopon lingulata von Meyer, 1858 ; Prosopon wuergauensis Kuhn, 1939 ); T. schweitzerae Starzyk, 2016 ; T. starzykae Schweitzer, Feldmann, Lazăr, Schweigert, and Franţescu, 2018 ; T. weinschenki sp. nov.

Remarks. Morphological differences between Tanidromites scheffnerae and T. wysokaensis are mentioned to include the rostrum being more sharply ended for T. scheffnerae (Starzyk, 2016) . However, the rostrum is incomplete or not prepared fully for all figured specimens (including all types) of T. wysokaensis nor in any of the other available specimens (pers. obs. NS). None of the specimens from Ernstbrunn have the rostrum fully preserved either. Tanidromites scheffnerae would have mesogastric groove tubercles said to be absent in T. wysokaensis (Starzyk, 2016) . However, figure 4.1 in Starzyk (2016) indicates the presence of such a tubercle in T. wysokaensis and a re-examination of paratype (I-F/MP/6263/1588/ 11) also reveals such tubercles. No new differences were found upon a re-examination of one Polish Oxfordian specimen of each species ( T. wysokaensis : I-F/MP/6263/1588/11; T. scheffnerae : I-F/MP/6261/1588/11). Because the orbital structure, one of the prime characters to distinguish species within Tanidromites (Starzyk, 2013, 2015a, 2016), is also identical, we consider T. wysokaensis as a junior synonym of T. scheffnerae .

Although the highly deformed holotype of T. schweitzerae has a shape, groove structure, and groove depth similar to T. alexandrae, Starzyk (2016) mentioned the more extended lower orbital margin, a short and blunt rostrum, and the elongated, less rounded epibranchial regions of T. schweitzerae to represent differences. The strong extension of the lower orbital margin can, at least in part, be explained by the fact that the orbital structure contains fractures resulting in this margin being flipped more forwardly. A blunt tip of the rostrum is also seen in T. alexandrae , and re-examination of the holotype of T. schweitzerae does reveal a hepatic pit, as found for T. alexandrae . The mesogastric groove tubercles are not always discernible for T. alexandrae either. The less rounded shape of the epibranchial region may be attributed to the deformed nature of the holotype because the paratype I-F/MP/4562/1534/08 of T. schweitzerae is indeed more rounded. These similarities beg the question whether T. schweitzerae is a junior synonym of T. alexandrae . A key difference remaining is the upper orbital margin that appears smooth in T. schweitzerae but contains some tubercles in T. alexandrae . Furthermore, the extension of the lower orbital margin in T. schweitzerae appears more prominent than in T. alexandrae despite the deformation that enhances this difference. Finally, although size is often not appropriate to use as a difference between species, it is notable that two of three specimens of T. schweitzerae , though incomplete, are larger (see Starzyk, 2016, table 1) than all 23 specimens of T. alexandrae with maximum carapace length of 9.6 mm (Starzyk, 2015a). Small, complete specimens of T. schweitzerae are required to further assess differences and similarities for similar-sized specimens because the relatively small specimen (I-F/MP/ 4562/1534/08) is incomplete and indented near the left hepatic region and orbital structure. Until then, we maintain the two species separate.