Common name

Common name : Giant devilray.

Nomenclatural discussion: In order to understand the complicated taxonomic history of M. mobular , it is necessary to go back to the original record upon which several authors based their descriptions. Duhamel du Monceau (1780) provided illustrations and a description of a specimen caught in 1723 near Marseille in southern France (Mediterranean Sea). The description includes some basic morphometrics, including length from head to tail (6 ft. = ~ 183 cm), mouth width (15 in. = 38 cm), each wing (6 ft. = ~ 183 cm) and tail (4.5 ft. = ~ 137 cm). The dorsal and ventral illustrations provided by Duhamel du Monceau show a subterminal mouth clearly indicating a Mobula , but strangely the ventral surface depicts six gill slits on each side. In Duhamel du Monceau’s account, reference is made to the Azores where it is referred to as Raie cornue (= horned ray) and the Caribbean where it is referred to as Mobular, and some that refer to it as Squatina. In the addition section of Duhamel du Monceau (1780, 330), reference is made to Gentil’s (1779) records of Diable de mer from the Indian Ocean which he alludes to being the same as his species. Gentil’s illustration of Diable de mer, although somewhat cartoonish, agrees with the overall shape of a mobulid, but not enough key features are apparent to determine the species. Duhamel du Monceau’s Raie cornue is not considered an available name as it was used in the vernacular in reference to the horned rays of the Azores.

Raja mobular was proposed by Bonnaterre (1788) for Duhamel du Monceau’s (1780) Marseille record, with the measurements provided taken from that publication. In the same year, Schneider provided a detailed account of Duhamel du Monceau’s description of the Marseille specimen, the Azores Raie cornue, and noting Gentil’s record of Diable de Mer from the Indian Ocean. In this publication, Schneider (1788: 82, 83) proposes the name Raia vespertilio for this species in allusion to its bat-like appearance. Walbaum (1792) listed Raja vespertilio as a questionable species.

Shaw (1804) described R. diabolus based on literature sources. The primary literature source was the account of Duhamel du Monceau (1780), based on the same specimen used for the R. mobular description by Bonnaterre (1788). The specimen was stated as being 10.5 ft. long (~ 320 cm) which matches the measurements provided for R. mobular , that is, tail length 4.5 ft. and body length 6 ft. Shaw included Russell’s ‘Eereegoodee Tenkoo’ in the synonymy and stated that it occurs in the Mediterranean, Atlantic and Indian seas, but mainly observed around the Azores. The distribution provided is likely based on Russell’s Indian species (Indian seas), the Marseilles specimen described by Duhamel du Monceau (Mediterranean) and the Azores records (Atlantic). Based on the Mediterranean location and the large size of the Marseilles specimen, Notarbartolo di Sciara (1987) included it in the synonymy of M. mobular ( Bonnaterre, 1788) . Since the descriptive characters used in this description are based on the same specimen used to describe M. mobular , R. diabolus must be considered a junior synonym of this species. Interestingly, Shaw’s description states that the tail is unarmed, whereas M. mobular possesses a distinct caudal spine. Another uncertainty is the coloration which is stated by Shaw as being cinereous brown above, whereas M. mobular is typically bluish black above. It is possible that the caudal spine was removed or missing from the Marseilles specimen or simply that Duhamel du Monceau did not include that feature in his description.

Klunzinger (1871) described Dicerobatis monstrum based on a 54 cm embryo that came from a 2 m female specimen stranded at Al-Qusair, Egypt, in the Red Sea. The holotype was listed as not found and probably lost by Fricke (1992). Dor (1984) considered this species a junior synonym of M. diabolus . The description includes reference to the spiracles being located behind the eyes on the back (i.e. not beneath the pectoral-fin origin) and the dorsal colour being blue black. These characters are adequate to confirm the identity of this species as M. mobular .

In 1841, Müller & Henle described a new species, Cephaloptera japanica , based on two specimens collected off Nagasaki in Japan. The brief description provides mostly generic-level features, but examination of the dried lectotype ( Fig. 8 View Figure 8 ) revealed the following key diagnostic features: white-tipped dorsal fin, serrated caudal spine behind dorsal fin, spiracles located above pectoral-fin origin, pectoral fins not strongly falcate and their anterior margins nearly straight (not concave). Mobula japanica is currently recognized as a wide-ranging, almost circumtropical species which is reported to attain at least 310 cm DW. In a revision of the genus, Notarbartolo di Sciara’s (1987) states that M. japanica does not differ substantially in any characters from M. mobular from the Mediterranean. The only character found to differ was the morphology of the rete mirabile cranica and possibly in tooth morphology, but this was based on limited data. Although retaining them as separate species, Notarbartolo di Sciara states that this is only due to lack of direct examination of a sufficient number specimens. This study provides new information to support the synonymization of these two species, with precedence given to M. mobular ( Bonnaterre, 1788) and Mobula japanica a junior synonym.

Cadenat (1959) described Mobula rancureli based on a single 2.4 m DW individual from off the Ivory Coast. Although considered a synonym of M. japanica by Notarbartolo di Sciara (1987), McEachran & Séret (1990) considered it to be a valid species. Cadenat (1959) distinguished this species from M. mobular based on the number of teeth and denticle morphology. Given this is only based on one specimen and these characters can vary greatly intraspecifically, this species should be considered a synonym of M. mobular .

A number of other names have been considered junior synonyms of M. mobular :

• Squalus edentulus was described by Brünnich (1768). The brief Latin description includes ‘ Squalus View in CoL capite lato, plano, maxillis osseis edentulis, superiore longiore, lateribus capitis prominentibus ’ which roughly translates to ‘ Squalus View in CoL with a wide head, flat, toothless bony jaws, the long sides of the head are prominent’. It was based on a specimen from Marseille which had head width equal to 3 ‘span’ (~ 68 cm based on a span equalling 9 in.), thus was referring to a large species. There is also reference to the upper jaw being file-like (rough surface) which possibly indicates that teeth are present which would rule out M. alfredi View in CoL and M. birostris View in CoL , which lack teeth in the upper jaw. Based on the location and size, this species is probably a synonym for M. mobular . Despite being an older name, S. edentulus has not been used as a valid name for this species and prevailing usage should be given to M. mobular ( Bonnaterre, 1788) .

• Aodon cornu Lacepède, 1798 View in CoL is an unneeded new name for S. edentulus Brünnich, 1768 .

• Raia aurita Suckow, 1799 appears to be based on Duhamel du Monceau’s specimen, as the latter record is included in the synonymy and the briefly described specimen is of the same proportions as the Marseille specimen (i.e. each wing 6 ft. wide). Bonnaterre’s Mobular is also listed in the synonym together with R. vespertilio . This name should be considered synonymous with M. mobular as it is evident that it is based on the same literature sources as previous names and thus is an unneeded replacement name for M. mobular Bonnaterre, 1788 .

• Raja cephaloptera Bloch & Schneider, 1801 , also refers to the Duhamel du Monceau specimen from Marseille and provides a type (only the forepart of the skull) which is from Schneider in Leipzig also. This species was stated to occur mostly in the Pacific .

• Raja fabroniana was described and illustrated by Lacepède (1800) from off Livorno, Italy. The illustration clearly depicts a large Mobula View in CoL with a subterminal mouth and the large size (~ 4 m DW) and Mediterranean location confirm it as a junior synonym of M. mobular .

• Raja giorna was described by Lacepède (1803) from the Bay of Nice in southern France. The illustration provided for this species includes a serrated caudal spine, thus confirming it as a junior synonym of M. mobular .

• Cephalopterus massena was described by Risso (1810) from off Nice in southern France based on a large specimen, but with no types designated and no illustration provided. The large size and Mediterranean location strongly suggest this to be a junior synonym of M. mobular .

• Apterurus fabroni Rafinesque, 1810 View in CoL is an unjustified emendation of Raja fabroniana Lacepède, 1800 .

• Mobula auriculata Rafinesque, 1810 View in CoL is based on Raja mobula of Lacepède according to Eschmeyer (2015).

• Raia cornuta is considered a new name combination in Lesueur (1824), in his account of Cephaloptera giorna View in CoL from off the Atlantic US coast, in reference to the Azores species. It does not appear that Lesueur intended to provide a new name combination and given it is based on the Azores species, it is possibly a synonym of M. mobular . However, it should be noted that the species referred to by Lesueur as C. giorna View in CoL from the US coast is considered a synonym of Mobula sp. cf. birostris ( Marshall et al., 2009) View in CoL . It is most likely that Lesueur was referring to Duhamel du Monceau’s Raie cornue, upon which a number of the synonyms of M. mobular were based.

• Cephalopterus edentula Griffini, 1903 View in CoL , was a new name combination for Brünnich’s Squalus edentulus , thus is also a junior synonym of M. mobular .

Remarks: Mobula mobular and Mobula japanica were previously considered distinct species. In Notarbartolo di Sciara’s detailed 1987 revision of the genus, he stated that the two species are very similar and possibly conspecific, but retained them as separate species pending more information. Due to the large size of these species, obtaining accurate material for comparison is relatively difficult. However, recently acquired molecular information has provided critical new information. These two taxa are very closely related based on the analyses of both mitochondrial genomes and nuclear exons (p -distance = 0.002 and 0.005 for mitogenome and nuclear datasets, respectively, Figs 1 View Figure 1 , 2 View Figure 2 ). Moreover, the expanded sampling of NADH2 data for these taxa revealed genetic distances that were consistently within the range of intraspecific divergences that were observed for taxa with uncontested specific status. Mobula mobular is considered to be a larger species with a maximum width of 520 cm, but mostly smaller ( Ebert & Stehmann, 2013) while M. japanica is reported to attain only 310 cm DW. However, this variation in maximum size is not an adequate specific character and likely reflects the variability in maximum size in large members of this family, as evidenced by M. birostris ( Walbaum, 1792) which has been reported to be as large as 910 cm DW, but is rarely found over 600 cm DW ( Marshall et al., 2009).

The only characters provided by Notarbartolo di Sciara (1987) to distinguish these two species were the morphology of the rete mirabile cranica and the teeth, but these were based only on a single specimen. Teeth can vary greatly in morphology within a species depending on size and sex. The teeth of M. japanica examined by Notarbartolo di Sciara (1987) were from two adult specimens, while examination of the teeth of M. mobular was based on a single juvenile specimen. Based on the lack of any substantial distinguishing features to separate these two species and the genetic results available, these two species are herein considered conspecific, with M. mobular ( Bonnaterre, 1788) given precedence.

OTHER AVAILABLE MOBULID NAMES

The following available binomial names for the Mobulidae cannot be accurately assigned to recognized species based on the limited descriptive data available in the original descriptions:

• Raja monstrosa Walbaum, 1792 was listed as a questionable species by Walbaum (1792) without location. The characters provided do not allow its identity to be determined and thus should be considered nomen dubium.

• Raja banksiana Lacepède, 1800 was described from an illustration of a specimen observed in the East Indies ( Indonesia?). The illustration is somewhat cartoonish, with the cephalic lobes both with long filaments, eyes located dorsally, no dorsal fin and elongate markings on the dorsal surface. But Lacepède noted that the illustration of this species was drawn from a specimen swimming, and thus the cephalic filaments are likely the result of distortion through the sea surface. As a result, the identity of the mobulid species drawn cannot be accurately determined and should be considered nomen dubium.

• Raja barbata was briefly described by Bloch & Schneider (1801) from the African sea, but the characters provided do not allow for accurate identification of the species and thus should be considered nomen dubium.

• Ceratoptera lesueurii was designated in Swainson (1839), as a footnote in a brief description of the genus Ceratoptera Müller & Henle, 1837 . The illustration of the head clearly depicts a Manta species, but it is not possible to determine which species and thus should be considered nomen dubium.