Coelogynopora schockaerti n. sp. (Proseriata: Coelogynoporidae), a remnant of a platyhelminth coldwater fauna in the northwestern Mediterranean?

Abstract

Coelogynopora schockaerti n. sp. (Proseriata: Coelogynoporidae) is described from the northwestern Gulf of Lion, Mediterranean. Only a few representatives of this genus are reported from Mediterranean marine sandy shores and only from the northwestern to central Mediterranean, but all of these species also occur outside the Mediterranean. So far, C. schockaerti n. sp. is the only species exclusively known from the Mediterranean. The species is solely encountered in the Gulf of Lion, a coldwater pocket in the Mediterranean and can, therefore, be considered as a remnant of an ancient coldwater platyhelminth fauna. C. schockaerti n. sp. is characterized by the shape and size of the spines of the male copulatory organ and the presence, orientation, shape and size of the two accessory spines. An identification key is given for the entire genus.

First discovery – and a new species – of Coelogynopora (Platyhelminthes, Proseriata) in the Southern Hemisphere

“…Therefore, it is impossible to confirm whether the new species is more closely related to its Pacific congeners than to the Atlantic ones, as the morphological characters suggest. Karling (1966), Sopott-Ehlers (1976, 1992, Tajika (1978Tajika ( , 1981, Riser (1981), Ax & Armonies (1987), Ax (2008), Armonies (2017Armonies ( , 2018, Jouk et al (2019), and this work.…”

“…This is further supported by the fact that C. kenichii sp. nov. and its northern congeners are present almost exclusively in cold waters and, interestingly, in only the Northern sector of the Mediterranean Sea (Jouk et al 2019).…”

“…There are currently 39 known species of Coelogynopora (Armonies 2018;Jouk et al 2019), but, besides C. kenichii sp. nov., only three other species have all the spines fused proximally with the base of the penial stylet, namely Coelogynopora alata Tajika, 1981, Coelogynopora brachystyla Karling, 1966and Coelogynopora coniuncta Tajika, 1978.…”

“…Coelogynoporidae (Platyhelminthes) includes comparatively large and slender Proseriata, usually occurring in shallow benthic environments. Among the representatives of the family, Coelogynopora Steinböck, 1924 is the most frequently reported genus and the one with the highest number of species (Jouk et al 2007(Jouk et al , 2019; Armonies 2017Armonies , 2018. The highest diversity in the genus is reached at high latitudes, and the 38 previously known, valid species have a strictly Northern Hemispheric distribution (for recent examples, see Curini-Galletti et al 2010; Armonies 2017Armonies , 2018Jouk et al 2019).…”

“…Fig.6. Map showing the known distribution of the genus Coelogynopora based on all the available reports, which may be summarised byKarling (1966),Sopott-Ehlers (1976, 1992,Tajika (1978Tajika ( , 1981,Riser (1981),Ax & Armonies (1987),Ax (2008),Armonies (2017Armonies ( , 2018,Jouk et al (2019), and this work.…”