Echinoplana celerrima Haswell 1907

Echinoplana celerrima Haswell, 1907 Fig. 10 Material examined. • MNHNC MB 16-000104, Station 7, 13 May 2018, 16 mm long. All the measurements from the description refer to this specimen; • MNCN 4.01/3983, Station 11, 19 February 2015, 9 mm long. Morphology. Elongated worm, wider in the anterior margin with a blunt end (Fig. 10 A). Length between 9 and 16 mm alive (12.5 ± 4.95 mm). Dorsal colour caramel and translucent intestinal branches are easily observed and vary from brown to green. Central part of the body darkish brown. Tentacles absent. Tentacular and cerebral eye clusters present, distributed parallelly and in two long rows (Fig. 10 B). Tentacular and cerebral eyes clustered in approximately 32 and 43 eyes, respectively. Pharynx ruffled, located in the second third of the body. Oral pore in the last third of the pharynx. Reproductive system. Genital pores separated (separated approximately 2.26 mm). Male apparatus (4.3 mm long) characterised by a seminal vesicle, an interpolated prostatic vesicle, and a conspicuous cirrus shown by transparency (Fig. 10 C). Female system with a large vagina (2.29 mm), a ductus vaginalis, and Lang’s vesicle in its distal region. Remarks. Echinoplana celerrima is the only species of the genus Echinoplana described by Haswell (1907) from Port Jackson, Sidney, Australia. After that, Galleni (1978) reported this species in the Port of Livorno, Italy, which was the first record of the species in the Mediterranean. Later, Holleman (2007) reported this species on the Pacific coast on the North Island of New Zealand. E. celerrima was also recorded in the lagoon of Tunis (Gammoudi et al. 2009; 2017) and now in the southern Iberian Peninsula (present study). Considering the geographical distance between the specimens from Australia, New Zealand, and the Mediterranean Sea, the contrast of information provided by the morphological characteristics and the DNA analyses (using nuclear and mitochondrial markers) is crucial to elucidating whether the populations belong to the same species. Biology. In this study, the specimens were collected under stones in the intertidal zone. Furthermore, Echinoplana celerrima frequently inhabits areas with human activity, such as harbours (Haswell 1907, Galleni 1978). Hence, the specimen of Sagres was precisely collected in a rocky area attached to a harbour zone, supporting one of the possible scenarios about the dispersion of this species (Prudhoe 1982). Distribution. As previously explained, Echinoplana celerrima is widely distributed on the southeastern coast of Australia (Haswell 1907; Prudhoe 1982; Johnston and Lee 2008; Rodríguez et al. 2021), Livorno, Italy (Galleni 1978), New Zealand (Holleman 2007), Tunisia (Gammoudi et al. 2009, 2017), and Catalonia, Spain (Gammoudi and Tekaya 2012). Our specimens provide the first reports of this species on the North-Atlantic shores of Portugal and Andalusia (Spain).