Ethusa undetermined
Creators: name: Guinot, Danièle
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Ethusidae
Ethusa
Ethusa undetermined

description: Ethusa sp.
Ethusa sp. – Pasini & Garassino 2016: 54, fig. 2. — Van Bakel et al. 2020: fig. 10.22.
REMARKS
This species, from the Pliocene of Valduggia (Vercelli, Piedmont) has been described as having “a pear-shaped carapace, wider posteriorly; dorsal regions well defined by marked grooves, and developed branchial regions crossed transversely by two branchial grooves forming two ridges” (Pasini & Garassino 2016: 54). It shares some dorippid characters, e.g. the deep precervical and cardiac grooves; the marked rim along the concave posterior margin of the carapace. The two branchial ridges, which are not clearly visible in the photograph, are reminiscent of those present in Ethusa popognensis.
FOSSILS ASSIGNED TO TELAMONOCARCINIDAE LARGHI, 2004 Dorippoidea has been represented in the fossil record since the Early Aptian by the family Telamonocarcinidae, with Telamonocarcinus Larghi, 2004 as type genus. Initially considered a subfamily of Dorippidae (Larghi 2004; Schweitzer & Feldmann 2011a), it was elevated to family status by Guinot et al. (2013: 188, 268, 306), an action subsequently followed by all authors (Luque 2015; Jagt et al. 2015; Charbonnier et al. 2017; Van Bakel et al. 2020; Schweitzer et al. 2021: 5; Luque et al. 2021: fig. 5; Vega et al. 2022). The presence of an oxystomatous disposition is not supported by any figure, as the anterior part of the ventral surface is hardly preserved or too blurred in the fossils concerned, and is only presumed from the arrangement of the other structures.
Telamonocarcinus gambalatus Larghi, 2004, the type species of the genus, was established on the basis of abundant and well-preserved material from the Cenomanian of Lebanon, allowing the use of ventral morphology and appendages (Larghi 2004: 539, figs 5, 6, 7.2-7.8; see also Pasini & Garassino 2011: 237), then redescribed with numerous figures by Charbonnier et al. (2017: 207, figs 451-463). Reconstructions of the holotype (Larghi 2004: fig. 5; Charbonnier et al. 2017: fig. 457; Van Bakel et al. 2020: fig. 6B) and photographs of the holotype and paratypes (Luque 2015: fig. 2B; Charbonnier et al. 2017: figs 453-456; Van Bakel et al. 2020: fig. 6A; Schweitzer et al. 2021: fig. 2.5) depict a narrow crab, with a deeply grooved and ornamented dorsal surface, with obliquely oriented epibranchial region, deep orbits, long eyestalks, overdeveloped outer orbital teeth and (where known), non-chelate P4 and P5 dactyli. Charbonnier et al. (2017: 207), who examined the holotype and about 50 specimens from Lebanon, confirmed the main characters of T.gambalatus, as follows: carapace pyriform, heavily sculptured; dorsal surface with overall granular ornamentation; long, sharp outer orbital teeth directed outwardly; orbits broad and arcuate; eyes well developed; and P4 and P5 reduced, subdorsal/dorsal, with dactyli that are non-subchelate (as in ethusids). Charbonnier et al. (2017: 209) referred to the dactyli as ‘falciform’, which is not visible in photographs and not in Larghi’s 2004 reconstruction, reproduced by Charbonnier et al. (2017: fig. 457). The outline of the reconstructed T. gambalatus is reminiscent of extant ethusids but also of these dorippids with an elongated and anteriorly narrowed body, such as the extant species of the genus Dorippe (Figs 10; 12A; 14A, B; 15A, C, E, F). The ventral surface of a topotypic specimen illustrated by Guinot et al. (2019: fig. 15) shows a wide thoracic sternum and a posteriorly positioned male pleon, with six free somites plus the telson, and the tip of the telson just reaching suture 5/6. The non-subchelate ending, if preserved, is the most important difference from the Dorippidae (see Table 1).
Garassino et al. (2007: 45; see also Garassino et al. 2014a: table 1) discovered several specimens from the Cenomanian-Turonian of southern Morocco that they named Telamonocarcinus cf. gambalatus (previously ‘indeterminate crab’ of Garassino & Larghi 2000: fig. 2), with preservation of the carapaces, the first pleonal somites, and P2 and P3. Garassino et al. (2008: 61) suggested that this Moroccan crab might be the same as the poorly preserved “genus and species indeterminate” from the Upper Cretaceous (Cenomanian) of Egypt referred to Necrocarcinidae Förster, 1968 by Schweitzer et al. (2003: 890, figs 1, 2). Luque (2015: 257), on the other hand, attributed the Egyptian taxon to Tepexicarcinidae until better material became available for study. Charbonnier et al. (2017: 207) considered that T. cf. gambalatus of Morocco was not different from T. gambalatus from Lebanon, without addressing the case of the enigmatic crab of Schweitzer et al. (2003).
Telamonocarcinus antiquus Luque, 2015 (Luque 2015: fig.2A; Luque et al. 2017: fig. 8D; Van Bakel et al. 2020: figs 6G, 10.7), from the Upper Aptian-Lower Albian of Santander, Colombia, known only by its wide carapace, with a concave, rimmed dorippid-like posterior margin and the presence of a distinct precervical groove, represented the oldest eubrachyuran known at that time according to Luque et al. (2017: 2) and Van Bakel et al. (2020: fig. 10.7). This species does not conform to Larghi’s 2004 reconstruction of the holotype of T. gambalatus, and, as only its dorsal carapace is known, it cannot be assumed that P4 and P5 are not subchelate, one of the main features that distinguishes the Telamonocarcinidae from the Dorippidae and shared with Ethusidae. There is a clear precervical groove and a narrow epibrachial region obliquely oriented like in extant dorippids (see Interpretation of grooves on the carapace dorsal surface in Dorippidae, see fig. 5B-D). It could well be a dorippid.
In contrast, Telamonocarcinus sp. of Luque (2015: fig. 2C, D, table 1; see Van Bakel et al. 2020: fig. 10.7), from the Cenomanian of Japan, Mikasa City, with its narrow carapace, developed outer orbital teeth and dorsal sculpture, is consistent with Larghi’s 2004 (fig. 5) reconstruction of the holotype of T. gambalatus. It would be important to ensure in well-preserved specimens that P4 and P5 are not chelated, a feature shared by telamonocarcinids and ethusids.
A second genus assigned to the Telamonocarcinidae is Eodorippe Glaessner, 1980 (p. 185, 186, 187), initially considered a podotreme included in the Torynommatidae by Glaessner (1980) (for the spelling Torynommatidae instead of Torynommidae, see the Code 1999, Art. 29; Collins 2003: 85; Guinot et al. 2013: 175), hence his hypothesis of “a Late Cretaceous origination of the heterotrematous Dorippidae from Tymoloidea” (i.e., Cyclodorippoidea Ortmann, 1892). Glaessner (1980: 186), who noted the “striking resemblance between the carapaces of Eodorippe and the genus Dorippe ”, also referred to “some resemblances between Eodorippe and Palicus Philippi, 1838 ”, concurring with our view that Palicoidea and Dorippoidea share similarities or analogies (Guinot et al. 2013: 212). The type species, Eodorippe spedeni Glaessner, 1980 (Glaessner 1980: 183, figs 13, 13A) from the Upper Cretaceous (Campanian-Maastrichtian) of New Zealand, has a well-preserved, typically dorippid carapace, with the deeply emarginated posterior margin that characterises older forms. The ‘rostrum long and narrow, spatulate, pointing forward’ shown in the sketch of Glaessner (1980: fig. 13A) does correspond to the anterior region of the carapace and probably not –as in our earlier misinterpretation (see Guinot et al. 2013: 188, 189) – to the anterior projection of the endostomal gutter into the median incision of the front visible dorsally to a variable extent in Recent dorippids. The anterior groove on the carapace dorsal surface, delimiting a narrow, obliqley oriented epibranchial region, is convex and can be termed ‘precervical’ as in extant dorippids (see Interpretation of grooves on the carapace dorsal surface in Dorippidae, Fig. 5 B-D), and is a strong evidence for a dorippid origin. The ventral characters and pereiopods are missing. The new figure and redescription of the holotype (with a ‘long rostrum’) by Luque (2015: 256, fig. 2E) and Schweitzer et al. (2021: 6, fig. 1.4) support the hypothesis of a close relationship of E. spedeni with the Dorippidae. It is even questionable which main differences prevent it from belonging to the Dorippidae. The carapace of the holotype of E. spedeni and that of the holotype of Telamonocarcinus antiquus (Lower Cretaceous, Upper Aptian-Lower Albian of Colombia), placed side by side by Van Bakel et al. (2020: figs 6F and 6G, respectively), clearly show the proximity of the two species.
In adding a second species to Eodorippe, E. binodosa Collins, Kane & Karasawa, 1993, from the Cenomanian of Japan, Collins et al. (1993: 303, fig. 2.6) took the same view, also emphasising the similarity to the Dorippidae. Eodorippe binodosa, initially considered a podotreme in Cyclodorippoidea by Collins et al. (1993: 303) and assigned to the Telamonocarcinidae by Larghi (2004: 535), Guinot et al. (2013: 188, as Telamonocarcinus binodosus), Luque (2015: 256, fig. 2F), and Van Bakel et al. (2020: fig. 10.10), is indeed another thing. In our opinion, E. binodosa differs from Eodorippe spedeni by its subrectangular carapace (versus almost as wide as long in E. spedeni), its short rostrum (versus long in E. spedeni), and its dorsal surface with only shallow grooves (versus with conspicuous transverse grooves and ridges in E. spedeni). According to Luque (2015) Telamonocarcinus and Eodorippe, which occurred in both the Old and New Worlds, did not survive the K/Pg extinction.
Eodorippe connori Nyborg, Garassino, Vega & Kovalchuck, 2019 (Nyborg et al. 2019a: 134, fig. 5), from the Albian of Oregon, USA, which probably corresponds to the unpublished reported occurrence of Eodorippe from the Cretaceous of Oregon by Schweitzer (2001: 812), is the earliest record of the genus Eodorippe. It is a large species (17 × 16 mm) with long, quadrangular P2 and P3 meri preserved. The narrow, forward-projecting front is not a typical feature of extant dorippids. The preservation of a rather large falciform detached piece in their fig. 5C, which is not mentioned by Nyborg et al. (2019b) nor by Van Bakel et al. (2020), could have been the only preserved element of a lost P4 or P5 of this species, i.e. a thick propodus and a developed dactylus. But the shape does not conform to the non-chelate P4 and P5 dactyli of Telamonocarcinus gambalatus, the type genus and species of Telamonocarcinidae, and this fragment is not part of E. connori. It belongs to another crab, most likely a palaeocorystid, such as Joeranina Van Bakel, Guinot & Artal, Fraaije & Jagt, 2012 or Eucorystes Bell, 1863 (see Van Bakel et al. 2012a) (Van Bakel, personal communication). We will see below that Van Bakel et al. (2020: fig. 10.4) assigned E. connori to the new genus Personadorippe Van Bakel, Mychko, Spiridonov, Jagt & Fraaije, 2021. The removal of E. connori from Eodorippe restores its monophyletic status to the Telamonocarcinidae.
Nyborg et al. (2019a: 134) compared E. connori to Withersella crepitans Wright & Collins, 1972, from the Lower Aptian (Lower Greensand) of the Isle of Wight, UK, the type species of Withersella Wright & Collins, 1972 (see also Wright 1997: 138, figs 12, 16), attributed to the Carcineretidae Beurlen, 1930 by Collins et al. 1995; Fraaje 1996; Wright 1997; Collins 2003), an assignment disputed by Glaessner (1980: 180). The genus was subsequently considered podotreme and assigned to the family Torynommatidae by Van Bakel et al. (2003), Schweitzer et al. (2007: 19), Schweitzer et al. (2010: 79), Schweitzer & Feldmann (2011b: 249, fig. 7), Karasawa et al. (2011b: 548), Klompmaker (2013: 173), and Collins et al. (2020: 40).
In addition, Van Bakel et al. (2020: 14) established a new telamonocarcinid genus, Personadorippe (type species P.kalashnikovi Van Bakel, Mychko, Spiridonov, Jagt & Fraaije, 2021; other species included: P. levashiensis Van Bakel, Mychko, Spiridonov, Jagt & Fraaije, 2020). Van Bakel et al. (2020: 15, 19, figs 9, 10.4) removed Eodorippe connori, the oldest record of Eodorippe, from the Telamonocarcinidae to include it in Personadorippe, the sister taxon to Eodorippe. In fact, Personadorippe connori (Nyborg, Garassino, Vega & Kovalchuck, 2019) shares some characters with P. kalashnikovi, established from a single carapace from the Upper Cretaceous, Lower Cenomanian, Moscow Oblast (Van Bakel et al. 2020: 15, figs 3A-D, 6D, 7A, 10.4, table 1; see also Schweitzer et al. 2021: fig. 5): similar carapace shape and ornamentation, subdivision of dorsal surface into regions, posterior margin with deeply concave and strongly developed rim.
Personadorippe levashiensis, from the Lower Cretaceous, middle Aptian strata, northern Caucasus (Van Bakel et al. 2020: 17, figs 3E, F, 5, 7B, 10.3, table 1), shows a slightly different groove pattern and carapace areolation (including a narrow, obliquely oriented epibranchial region), as well as a peculiar arrangement of granules. The posterior margin was described as “concave, inverted V-shaped, divided into two curved portions, with acute rim”: we wonder whether these ‘two curved portions’, clearly discernible in the photographs of Van Bakel et al. (2020: figs 3E, 7B), might not correspond to a developed strip in two parts as in the Recent Dorippe facchino (Fig. 8A), but it is more likely that they belong to the pleon. The preserved right chela of P. levashiensis (Van Bakel et al. 2020: fig 5), which consists of a compact propodus and long fingers, can be compared to the chelipeds of Telamonocarcinus gambalatus (Larghi 2004; Charbonnier et al. 2017). In Recent dorippids, heterochely with a robust major cheliped usually only appears in males that have reached a large size, depending on the species: in large males, the palm of the major cheliped becomes swollen, much higher than long, sometimes even with a bulbous ventrodistal protuberance, and the relatively short fingers form a slight angle with the palm axis. Chelae with a narrow palm and very long fingers like that of P. levashiensis are never found in dorippids.
Van Bakel et al. (2020: 11, 13, 18, figs 6E, 10.2) recently transferred Withersella to the Eubrachyura and included it in the family Telamonocarcinidae. Withersella crepitans has a square and flattened carapace with a long mesogastric anterior process, an axially sulcate rostrum, long outer orbital teeth, a rimmed posterior margin, some of these characters reminiscent of the features shared by telamonocarcinids and ethusids. Another former podotreme genus assigned to the Glaessneropsoidea Patrulius, 1959, in Longodromitidae (Klompmaker 2013; Schweitzer & Feldmann 2011b), Navarrara betsieae Klompmaker, 2013, from the Upper Albian, Eguino Formation of Koskobilo, northern Spain (Klompmaker 2013: 155, fig. 4, table 4), has recently been assigned to the Eubrachyura and included in the Dorippoidea within the Telamonocarcinidae by Van Bakel et al. (2020: 13, 15, figs 6C, 10.6). The carapace has a distinct outline, a quite different areolation of the dorsal surface and does not show the same groove pattern as other telamonocarcinids. In our opinion, the two monotypic genera Withersella and Navarrara Klompmaker, 2013 must still be able to justify their inclusion in the Dorippoidea. Withersella crepitans and Personadorippe levashiensis, supposed to represent the oldest dorippoids, may well be among the oldest eubrachyurans currently known, with the possible exception of the Hymenosomatidae recently discovered from the Barremian of Brazil by Mendes et al. (2022). It should be noted that Mendes et al. (2022: fig. 7) agreed with the inclusion of Withersella, Navarrara and Personadorippe into the Dorippoidea.
It is quite possible to recognise in Telamonocarcinus gambalatus, T. antiquus, Eodorippe spedeni and, to a lesser degree, in Personadorippe the dorippid groove pattern as we have interpreted it in the extant dorippids (see Interpretation of grooves on the carapace dorsal surface in Dorippidae and Fig. 5 B-D), i.e., a short, more or less convex precervical groove and a long cervical groove on a well areolated dorsal carapace, with a narrow, oblique epibranchial region, a mesogastric region extending almost to the front and a well-defined metagastric (plus urogastric) region. Although these grooves are less perceptible in some species, such as Eodorippe binodosa, there is no doubt that they belong to the same group, the Dorippoidea.
Once again, it must be recognised how misleading the carapace is. For example, a crab, such as Dioratiopus salebrosus Woods 1953 (p. 53, fig. 2, pl. 2, figs 4, 5) from the Upper Albian of Central Queensland, with several well-preserved parts, assigned to the Cymonomidae by Wright & Collins (1972: 33), synonymised with Glaessnerella Wright & Collins, 1975 (Glaessneria Wright & Collins, 1972) by Glaessner (1980) and now in the podotreme family Longodromitidae (Karasawa et al. 2011b: 536; Schweitzer et al. 2017: 216), has a carapace that somewhat resembles that of certain telamonocarcinids. But the gonopore on the coxa of P3 (Woods 1953: 54) precludes any relationship. Van Bakel et al. (2012b) considered that some species of Glaessnerella might turn out to be members of the Homoloidea, and Van Bakel et al. (2020: 19, fig. 9) left the question open pending a revision, whereas Starzyk et al. (2023) recently demonstrated that the genus Laeviprosopon Glaessner, 1933 does indeed belong to the Homolidae.
Telamonocarcinids share an additional feature, seemingly not yet reported, namely the presence of at least four strong and well-aligned tubercles behind the frontal region. Five, including the weaker latero-external one, in Telamonocarcinus gambalatus (see Larghi 2004: figs 5, 6.4; Luque 2015: fig. 2B; Charbonnier et al. 2017: figs 451-463; Van Bakel et al. 2020: fig. 6A, B), in T. antiquus (see Luque 2015: fig. 2A; Van Bakel et al. 2020: fig. 6G) and in Eodorippe spedeni, where there is even a row of eight subfrontal tubercules (see Luque 2015: fig. 2E; Van Bakel et al. 2020: fig. 6F). Both P. kalashnikovi and P. connori have four tubercles behind the front. Interestingly, there are four subfrontal tubercles in the dorippid Medorippe margaretha.
If the above-mentioned taxa prove to be true Dorippoidea, the family Telamonocarcinidae would be older than the Albian Componocancridae Feldmann, Schweitzer & Green, 2008. According to Van Bakel et al. (2020: fig. 10), Telamonocarcinidae, with its records from the Aptian, would represent the earliest confirmed crown- and stem-group Eubrachyura known to date.
The Dorippidae was recovered basal in the brachyuran phylogenetic tree of life by Luque et al. (2021: fig. 5). However, the discovery in the Late Barremian of Central Mexico of Cretamaja klompmakeri Vega, González-León & Moreno-Bedma, 2019 (Vega et al. 2019: figs 29-3), if it proves to be a majoid, would call this precedence into question. Indeed, the genus Cretamaja Klompmaker, 2013 (type-species C. granulata Klompmaker, 2013 from the Late Albian of northern Spain, Koskobilo quarry) is considered to be a majoid by some authors (e.g. Vega et al. 2019), which would assign the Majoidae an earlier record than the Dorippoidea. But first, we disagree with the placement of Cretamaja in the Priscinachidae Breton, 2009 (Breton 2009), their differences being ‘evident’ as noted by Klompmaker (2013: 169), and, on the other hand, we doubt the majoid status of Cretamaja, whose carapace is morphologically closer to that of some Longodromitidae, a paraphyletic family that is podotreme in whole or in part (thus included, in whole or in part, in the Dynomeniformia Guinot, Tavares & Castro, 2013) and that has been restricted and rediagnosed by Van Bakel et al. (2020: 3).
description: Published as part of Guinot, Danièle, 2023, A new subfamily classification of the highly diversified Dorippidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Dorippoidea), using morphological, molecular and palaeotonlogical data, with special emphasis on its unique female reproductive system, pp. 225-372 in Zoosystema 45 (9) on pages 364-367, DOI: 10.5252/zoosystema2023v45a9, http://zenodo.org/record/8071253