Thysanozoon brocchii ( Risso, 1818 )

Cuadrado, Daniel, Hernández-Gonzalez, Alejandro, Noreña, Carolina & Simões, Nuno, 2024, Polyclads (Platyhelminthes) in the southern Gulf of Mexico: unveiling biodiversity and descriptions of two new species, ZooKeys 1221, pp. 103-144 : 103-144

Thysanozoon brocchii ( Risso, 1818)

Fig. 16

Material examined.

Campeche coast, Mexico • 1; Cayo Arcas; 20.2 ° N, 92.0 ° W; 6.3 m; 22 Apr. 2018; A. Hernández leg.; CRPPY - 0068 • 1; Cayo Arcas; 20.2 ° N, 92.0 ° W; 13.2 m; 24 Apr. 2018; A. Hernández leg.; CRPPY - 0076 .

Distribution.

The species was described from Naples, Italy ( Risso 1818). It is considered a cosmopolitan species, reported in the Mediterranean Sea, the United Kingdom, and southern and western Africa. In the western Atlantic, Thysanozoon brocchii has been recorded in the Gulf of Mexico ( Hyman 1952; Marcus and Marcus 1968); Caribbean coast of Colombia ( Quiroga et al. 2004 a, 2004 b); Brazil ( Bahia et al. 2014, 2015, 2017; Bahia and Schrödl 2018); Canary Islands ( De Vera et al. 2009); Argentina ( Brusa et al. 2009). In the Pacific it has been recorded in Japan and New Zealand ( Prudhoe 1985). The record for Cayo Arcas, Campeche, represents the first record for Mexico.

Description.

Body oval-shaped and firm consistency, 1.5 cm in length and 0.5 cm in width. Background colour ranges from brown to yellowish-ochre. Two stripes of paler cream spots, one longitudinally and the other perpendicular, form an inverted cross (Fig. 16 A, B ). The dorsal surface is covered with characteristic papillae, decreasing in size towards the margin. Pseudotentacles complex with multiple folds (Fig. 16 D ). Ruffled pharynx located in the first 1 / 3 of the body, with the oral opening in the middle. Two male copulatory apparatus and positioned close to the female organ in the ventral central region of the body. Sucker at the beginning of the second 1 / 2 of the body (Fig. 16 C ).

Remarks.

Thysanozoon brocchii is noted for the abundance of papillae covering its dorsal surface and its cosmopolitan distribution. Various morphological descriptions with distinct colour patterns occur for different localities ( Bahia et al. 2014). Molecular analysis of the different populations of this species is needed to identify potential divergences among the cited locations.

Figures

Figure 16. Thysanozoon brocchii A dorsal view B In situ C ventral view D detail of the dorsal surface; papillae, cerebral eyes, and pseudotentacles.