Cycloporus papillosus
Creators: name: Dittmann, Isabel L.
name: Grosbusch, Alexandra L.
name: Bertemes, Philip
name: Egger, Bernhard
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Polycladida
Stylostomidae
Cycloporus
Cycloporus papillosus

description: History of Cycloporus papillosus /Differential diagnosis
So far, only one Cycloporus species, C. papillosus, was described from the Mediterranean, featuring the eponymous papillae (Lang 1884). A variety without papillae was named C. papillosus var. levigatus Lang (1884). Lang (1884) argued that based on the external appearance, C. papillosus could be classified into five to six different species, but decided against it due to the very similar internal morphology. In the meanwhile, the external morphology turned out to be an important character for the species determination of Cycloporus (Newman & Cannon 2002).
Lang described C. papillosus in 1884 and synonymised it with Proceros tuberculatus Schmidtlein, 1880. As Schmidtlein did not provide a description of P. tuberculatus, the material of which he had received from Lang (Schmidtlein 1880), P. tuberculatus is a nomen nudum and unavailable according to Article 12.1 of the International Code of Zoological Nomenclature (ICZN 1999). The formal species description under the name C. papillosus was published in Lang (1884). Some years later, Francotte (1897) found that Lang’s description of C. papillosus also fits the description of Planaria schlosseri Giard, 1873, and also observed variants without dorsal papillae. Bock (1913) synonymised Thysanozoon papillosus Sars, 1878 with C. papillosus of Lang (1884) as C. papillosus (Sars, 1878) and noted colour variants and specimens without dorsal papillae. He provided a photograph of a sagittal section through the genital region of C. papillosus but remained sceptical that Giard’s Planaria schlosseri was the same species as C. papillosus (Bock 1913). We therefore regard P. schlosseri as a nomen dubium. The latest study dealing with C. papillosus was conducted by Noreña et al. (2014), giving a detailed sagittal reconstruction of the genital region, and noting several colour variations, all with dorsal papillae (Noreña et al. 2014). All studied specimens of C. papillosus are from Atlantic coasts, with the exception of Lang (1884), who worked with material from the Mediterranean. Lang (1884) also introduced a variation without dorsal papillae under the name C. papillosus var. levigatus.
The size and colouration of C. pinkipus sp. n. differ from C. papillosus or C. papillosus var. levigatus. The latter have a length between 10 and 16 mm (except 5 mm in Bock 1913), while C. pinkipus sp. n. measures only between 2 and 4 mm. Lang (1884) describes the colouration of C. papillosus var. levigatus as transparent and slightly reddish, with yellow spots at the positions of the missing papillae, and yellow marginal pores. The carmine red intestinal branches dominate the colour pattern (Lang 1884, plate 8, fig. 5, Fig. 8). The observed colour patterns in C. papillosus are according to Lang (1884) white to yellow/orange, with either white or carmine red dorsal papillae; the marginal pores are conspicuously red-brown. The dorsal colour pattern in C. pinkipus sp. n. is similar to the written descriptions of C. papillosus, but the given pictures are dissimilar (Fig. 8), and there are no dorsal papillae in C. pinkipus sp. n. In addition, the marginal pores are colourless and inconspicuous in C. pinkipus sp. n., in contrast to C. papillosus. The colour patterns given for C. papillosus var. levigatus and C. pinkipus sp. n. are substantially different (Figs. 1–2; 8). Our molecular data also confirm the separation of the two species (Fig. 7).
description: Published as part of Dittmann, Isabel L., Grosbusch, Alexandra L., Bertemes, Philip & Egger, Bernhard, 2023, A new species of Cycloporus from the Adriatic Sea, with an updated phylogeny of the families Euryleptidae and Stylostomidae (Polycladida, Platyhelminthes), pp. 235-248 in Zootaxa 5319 (2) on pages 242-244, DOI: 10.11646/zootaxa.5319.2.5, http://zenodo.org/record/8182500