Notas / Notes


First record of the elusive oceanic squid Thysanoteuthis rhombus Troschel, 1857 (Cephalopoda: Thysanoteuthidae) in the Catalan coast

Fernando Ángel Fernández-Álvarez1, Ana I. Colmenero2 & Claudio Barría3

1 Ryan Institute and School of Natural Sciences, National University of Ireland Galway, Galway, H91 TK33, Ireland
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2 Institut de Ciències del Mar, CSIC, Passeig Maritim de la Barceloneta 37–49, 08003 Barcelona, Spain
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3 Institut de Ciències del Mar, CSIC, Passeig Maritim de la Barceloneta 37–49, 08003 Barcelona Spain
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The diamondback squid Thysanoteuthis rhombus Troschel, 1857 is a large and elusive oceanic squid species. Here, we provide the first record of the species for the Catalan coast and integrate this finding in the current knowledge of the species in close areas.

Keywords: Mediterranean Sea; Cephalopoda; Oegopsida; Thysanoteuthidae; first record.



Primera cita del elusivo calamar oceánico Thysanoteuthis rhombus Troschel, 1857 (Cephalopoda: Thysanoteuthidae) en la costa catalana

El chipirón volantín (Thysanoteuthis rhombus Troschel, 1857) es una especie de calamar oceánico grande y elusivo. En este trabajo se proporciona el primer registro de la especie para la costa catalana y se discute en el contexto de registros de la especie en zonas cercanas.

Palabras clave: Mar Mediterráneo; Cephalopoda; Oegopsida; Thysanoteuthidae; primera cita.


Recibido/Received: 13/04/2020; Aceptado/Accepted: 23/07/2020; Publicado en línea/Published online: 07/04/2021

Citation / Cómo citar este artículo: Fernández-Álvarez, F. A., Colmenero, A. I. & Barría, C. 2021. First record of the elusive oceanic squid Thysanoteuthis rhombus Troschel, 1857 (Cephalopoda: Thysanoteuthidae) in the Catalan coast. Graellsia, 77(1): e122.

Copyright: © 2021 SAM & CSIC. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0).







The diamondback squid Thysanoteuthis rhombus Troschel, 1857 is a large oceanic squid, which reach a maximum mantle length of 1 m and 30 kg of total weight (Jereb & Roper, 2010). It is considered a cosmopolitan species distributed worldwide in tropical and temperate open waters. The rhomboidal fins are large and extend all the length of the mantle, giving to this species a characteristic diamond shape. T. rhombus is known in the Mediterranean Sea since the XIX century (Troschel, 1857); however, its oceanic lifestyle hinders its detection. Although it is a common species in Mediterranean waters (Biagi & Bello, 2009), records are scattered in the scientific literature.

During the night of the 29th August 2017 a specimen of T. rhombus was caught in the fishing grounds off the Catalan coast in the northwestern Mediterranean Sea (40.75527° N, 1.34805° E) at seafloor depth of 180 m, by the purse seine fleet from the Port of Tarragona. It was an immature subadult (Fig. 1A), measuring 93 mm mantle length and 33 g of total weight. Its sex was not possible to visually assess due the lack of detectable gonads at a macroscopic level. In Table 1, the dorsal mantle length, the ventral mantle length, the maximum mantle width, the fin length, the fin width, the head length, the head width, the length of the right arms I-IV and the right tentacle are provided according with the guidelines of Roper & Voss (1983). The characteristic well-developed anal photophore of juveniles and early subadults was present (Fig. 1B). The stomach content weighted 0.94 g and was entirely formed by fish fragments, including 3 vertebrae and 5 bones (0.37 g). Unfortunately, no otolith was recovered and the fish remain unidentified.

Fig. 1.—Thysanoteuthis rhombus Troschel, 1857. A. Dorsal and ventral views of the specimen ICMC000069 (CBR-ICM, Barcelona, Spain). B. Dissection showing the distal portion of the digestive system, the anal photophore (p) is near the anus (a).

Fig. 1.—Thysanoteuthis rhombus Troschel, 1857. A. Vistas dorsal y ventral del espécimen ICMC000069 (CBR-ICM, Barcelona, España). B. Disección mostrando la parte distal del sistema digestivo, el fotóforo anal (p) se encuentra cerca del ano (a).


Table 1.—Morphometric measures of the Thysanoteuthis rhombus Troschel, 1857 specimen ICMC000069 (CBR-ICM, Barcelona, Spain) according with Roper & Voss (1983).

Tabla 1.—Medidas morfométricas del espécimen ICMC000069 de Thysanoteuthis rhombus Troschel, 1857 (CBR-ICM, Barcelona, España) de acuerdo con Roper & Voss (1983).

Variable Value (mm)
Dorsal mantle length 93
Ventral mantle length 96
Maximum mantle width 39
Fin length 87
Fin width 98
Head length 24
Head width 25
Right arm I length 21
Right arm II length 45
Right arm III length 79
Right arm IV length 32
Right tentacle length 138

Some previous records of T. rhombus are known for the Iberian waters. The first one consisted in a single large individual fished in Mahón (Minorca) in 1978 (Morales, 1981), followed by the record of an egg mass by Guerra & Rocha (1997). Guerra et al. (2002) reported four additional egg masses in Mediterranean waters and other four in the Canary Islands. Escánez Pérez et al. (2012) reported several egg masses in the Canary Islands. Three large specimens were also reported in the Cantabrian Sea (Guerra et al., 2012). In the last work, it is also mentioned the capture of two individuals of both sexes in a tuna net in Ceuta. Templado and Luque observed two additional individuals in the Almeria coast (Guerra, 1992). For a comprehensive list of Catalonian and Iberian cephalopods, see Sánchez (2009) and Guerra (1992), respectively. Zaragoza et al. (2015) recorded 56 T. rhombus paralarvae sampled in 2004 and 2005. The presence of paralarvae at least during two consecutive years near the Ibiza Channel (Zaragoza et al., 2015), as well as the egg mass at the South of the Balearic Islands (Guerra & Rocha, 1997) and the newly reported subadult from Tarragona suggest that T. rhombus might be a common resident of the Balearic Sea. Besides those Iberian records, the species have been cited in other areas of the Mediterranean Sea (Issel, 1920; Sanzo, 1929; Biagi, 1982; Vardala-Theodorou et al., 1991; Jereb & Ragonese, 1994; Ezzeddine-Najai, 1996; Giordano et al., 1998; Bello, 1999; Salman et al., 2003; Marčic et al., 2009; Thessalou-Legaki et al., 2012; Yahel et al., 2017). Its oceanic lifestyle together with the absence of any target jigging fishery for oceanic squids in the area (Jereb & Roper, 2010) might complicate further encounters with this large oceanic squid. Despite its size and palatability, only a targeted fishery occurs in Japanese waters (Arkhipkin et al., 2015), but small catches are also reported in Jamaica, the Canary Islands and India (Aiken et al., 2007; Escánez Pérez et al., 2012; Sajikumar et al., 2020).

Material examined. Unsexed individual. 29/08/2017, at night. 40.75527° N, 1.34805° E. Fished by a purse seine vessel at surface waters (seafloor at 180 m of depth). M. Hernández leg. Voucher accession number ICMC000069, Biological Reference Collections of the Institut de Ciències del Mar (CBR-ICM, Barcelona, Spain), formalin fixed.


Thanks to María Hernández (Confraria de Pescadors de Tarragona) for providing us with the T. rhombus specimen and the collecting data. Francisco Olivas performed the curation of the morphological voucher under the Biological Reference Collections (CBR-ICM). We thank two anonymous reviewers for their comments, which helped us to improve the quality of the manuscript. FAFA was supported by an Irish Research Council-Government of Ireland Postdoctoral Fellowship Award (Ref. GOIPD/2019/460).


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