Cadulus platensis Henderson, 1920

Souza, Leonardo S., Caetano, Carlos Henrique S., Scarabino, Fabrizio & Costa, Paulo Márcio S., 2020, New records and a new species of Scaphopoda (Mollusca) from the southwestern Atlantic Ocean, Iheringia, Série Zoologia (e 2020023) 110, pp. 1-12 : 4-7

Cadulus platensis Henderson, 1920

( Figs 19–27 )

Cadulus platensis HENDERSON, 1920:147 , pl. 20, fig. 14.

Cadulus platensis ― DALL,1927:19; SCARABINO,1970:41; 1975:182, pl. 58, fig. 884 [reproduced from original illustration]; 1985:201, pl. 73, fig. 1029 [reproduced from original illustration]; 1994:309, pl. 107, fig. 1517; STEINER & KABAT, 2001:440; 2004:631; SCARABINO, 2003:193; CAETANO & SCARABINO,2009:455 [fig. at the top of the page, not fig. 1287].

Type material. Holotype ( USNM 887476 , 1 shell) . Paratypes: from type locality, USNM 330845 [2 shells]; USA, Florida , off Fernandina, USBF sta. 2415, 30°44ʼN 79°26ʼW, 805 m [440 fms], coll. Steamer Albatross, 01/ iv/1885 ( USNM 108279 , 2 shells); Georgia, off Georgia, USBF sta. 2668,30°58ʼ30ˮN 79°38ʼ30ˮW, 538 m [294 fms], coll. Steamer Albatross, 05/v/1886 ( USNM 108172 , 7 shells; AMNH 148340 , 1 shell); BRAZIL, Ceará, USBF sta. 2760, 12°07ʼS 37°17ʼW, 1864 m [1019 fms], coll. Steamer Albatross, 18/xii/1887 ( USNM 95447 , 1 shell) .

Type locality. Originally stated as ARGENTINA, Buenos Aires, off Río de la Plata, USBF sta. 2764, 36°42ʼS 56°23ʼW, 21 m [11.5 fms]. Corrected to: BRAZIL, Rio de Janeiro, USBF sta. 2763, 24°17ʼS 42°48ʼW, 1228 m [671 fms] ( SCARABINO, 2003: footnote 3; see Remarks) .

Material examined. Type material. BRAZIL: São Paulo: off Santos (3059 m), coll. R / V Wladimir Besnard , 1975 ( MORG 20181 , 1 shell); off Santos , 23°57ʼS 46°19ʼW, 400 m, coll. R / V Wladimir Besnard ( MZSP 119362 †, 8 shells); Rio Grande do Sul: Rio Grande Rise , ERG sta. 001, 29°53ʼ24ˮS 36°39ʼ21ˮW, 1439–1689 m, coll. Supply Boat Astro Garoupa, 07/vi/2011 ( MNRJ 27204 †, 2 shells) .

Distribution. USA: Georgia, Florida; Brazil: Ceará ( HENDERSON, 1920), SÃo Paulo ( RIOS, 1994; CAETANO & SCARABINO, 2009), Rio Grande do Sul (Rio Grande Rise) (this study).

Remarks. The holotype of C. platensis ( USNM 887476) ( Figs 19–22 ) and two other paratypes ( USNM 330845) were supposedly collected off “Río de la Plata”, Argentina ( USBF sta. 2764), a shallow locality, while the other records were in bathyal depths. HENDERSON (1920:15) himself doubted the reliability of the record: “A false note is touched in an 11-fathom station off Rio de la Plata quoted four times in our table, and in each instance for deep-water species of other stations. I feel quite sure that some error has been made in recording this station (No. 2714) [sic, misquote for 2764] by the United States Fish Commission”. The same doubt was raised by QUINN (1979:14–15; 1983:358–361) for records of some Vetigastropoda.

TOWNSEND (1901) reported that the same sampling equipment was used in the USBF sta. 2763 and sta. 2764, which were sequentially sampled and may lead to a contamination of the samples. Based on these doubts and facts, SCARABINO (2003:193, footnote 3) corrected the type locality of C. platensis to off Rio de Janeiro, Brazil, at the USBF sta. 2763. Furthermore, the latter author also supported his decision based on the presence of this species in samples collected off Rio de Janeiro during the MD 55 expedition. There are similar cases of gastropods collected from the same locality, as Carenzia trispinosa (Watson, 1879) and Pendroma perplexum Dall, 1927 . Carenzia trispinosa was recorded by QUINN (1979) at the USBF sta. 2764, and is also known from samples collected by the MD 55 expedition off Rio de Janeiro ( SALVADOR et al., 2014). However, in the case of this gastropod, SALVADOR et al. (2014) did not discuss about the presence of the species in the USBF sta. 2764 and considered the distribution of Carenzia trispinosa in Argentina, although not including the shallow record in the bathymetric range of the species. Pendroma perplexum is also known from samples of the MD 55 (F. Scarabino, pers. obs.) and belongs to a family constituted by bathyal species ( Pendromidae ; WARÉN 1991). These cases reinforce SCARABINO’s (2003) hypothesis about the correct type locality of C. platensis .

Based on the explanations above, the southernmost record of C. platensis is currently off SÃo Paulo state, Brazil ( SCARABINO, 1994; CAETANO & SCARABINO, 2009). CAETANO & SCARABINO (2009:455) presented confusing figures and the order of the images are corrected here to avoid confusions: from the top of the page, the species figured are Cadulus platensis , Gadila braziliensis ( Henderson, 1920) , Gadila dominguensis (d’Orbigny, 1842) and Cadulus parvus Henderson, 1920 .

In the present study, we report a new record of C. platensis in the Rio Grande Rise, South Atlantic, extending the geographic distribution of the species southward. The two shells collected there ( Figs 23–26 ) closely resemble the morphology of the holotype of C. platensis ( Figs 19–22 ). One of the shells from Rio Grande Rise is a younger specimen ( Figs 25, 26 ), but the largest one ( Figs 23, 24 ) presents similar dimensions with the holotype ( Tab. I).

The present species is closely related to Cadulus tumidosus Jeffreys, 1877 ( Figs 28–35 ), from eastern Atlantic, regarding shell morphology. HENDERSON (1920) recognized these similarities and the shape variation at the equator in both of them, but preferred to separate the western Atlantic specimens introducing a new name. HENDERSON (1920) described C. platensis with a somewhat larger shell than C. tumidosus , but the dimensions are very similar. We add that C. platensis can be distinguished by the slowly reduction of the diameter of the shell towards the dorsal aperture ( Figs 19, 23, 25, 27 ), while this reduction is more abrupt in C. tumidosus ( Figs 28, 30, 32, 34 ).

Figures

Figs 19–27. Cadulus platensis Henderson, 1920. 19–22, holotype (USNM 887476); 23–26, MNRJ 27204: 23, 24, same shell; 25, 26, same shell; 27, MZSP 119362.19, 23, 25, 27, entire shell, lateral view; 20, 24, 26, entire shell, anterior view; 21, detail of dorsal aperture; 24, detail of ventral aperture. Scale bars: 19, 20,23–27= 1 mm; 21, 22= 0.4 mm.

Figs 28–35. Cadulus tumidosus Jeffreys, 1877: syntypes (USNM 169502): 28, 29, same shell; 30, 31, same shell; 32, 33, same shell; 34, 35, same shell. 28, 30, 32, 34, entire shell, lateral view. 29, 31, 33, 35, entire shell, anterior view. Scale bar: 2 mm (all images at same scale).