Bioacoustics of Arctocypris edita

Remarks. Specimens of this species are represented by two colour types , green (from sites OS11-29, 80; Table 1 ) and white (sites OS11-9, 11). As there are no obvious morphological differences in carapace shape and chaetotaxy, or size between the two types , we conclude they are conspecific. Differences in the colour of specimens may be related to environmental factors, and similar colour variations have been recorded in other species (e.g. Dolerocypris ikeyai Smith & Kamiya, 2006 ; Smith 2011 ). Of the five other species in the genus Arctocypris , three are extant and two are known from valves only. Arctocypris fuhrmanni and A. arctica are found living in Spitsbergen ( Olofsson 1918 ; Petkovski et al. 2016 ), while A. mareotica comb. nov. is living in North Africa, parts of Europe, and Central Asia (see review of distribution in Rasouli et al. 2016 ). Valves of A. mareotica comb. nov. from modern sediments have also been recorded from the Tibetan Plateau (e.g. Li et al. 2010 ; Song & Wang 2014; Song et al. 2015a ; 2015b ; Zhang et al. 2013 ). Arctocypris foveata and A. dulcifons were originally reported from Pleistocene deposits in Canada and Germany respectively, with valves of A. dulcifons later found in Siberia and the Qinghai region of China ( Mischke et al. 2003 ; Wetterich et al . 2005 ; Li et al. 2010 ). Arctocypris edita n. sp. resembles the type species of the genus, A. fuhrmanni , with an overall similar lateral view of the carapace, similar number and positions of inner lists on the calcified inner lamellas of both valves and similar chaetotaxy of the appendages. Compared to Arctocypris edita n. sp. , the carapace of A. fuhrmanni is noticeably less elongate, the dorsal margin more angular and the surface ornamentation more pronounced. The appendages of both species are a close match, but they differ in the length of the A1 y a aesthetasc: this is about twice as long as the terminal segment in A. fuhrmanni (remeasured from the type specimens, somewhat longer than that figured in the original description by Petkovski et al. (2016) —B. Scharf, Bremen , Germany , pers. comm.), but 3–4 times the length of the terminal segment in Arctocypris edita n. sp. The numbers of setae/claws on the terminal segment of the Mx are five in both species (four was reported for A. fuhrmanni by Petkovski et al. (2016) , but there are actually five—B. Scharf, Bremen , Germany , pers. comm.). Both tooth bristles on the third endite of the Mx are serrated in A. fuhrmanni , but in Arctocypris edita n. sp. the tooth bristles are rather variable in the amount of serration expressed. Arctocypris arctica and A. mareotica comb. nov. are both smooth and have different lateral outlines of the valves compared to Arctocypris edita n. sp. The original description of A. dulcifons shows a species that is noticeably less elongate than Arctocypris edita n. sp. ( Diebel & Pietrzeniuk, 1969 ), but later reports of this species figure slightly more elongate specimens (e.g. Wetterich et al. 2005 ; Fuhrmann 2012 ). This species can be distinguished from Arctocypris edita n. sp. by its more inflated postero-ventral margin, straighter postero-dorsal margin, stronger ornamentation, less laterally compressed anterior and less elongate lateral outline. Arctocypris foveata is the least elongate species in the genus, with a rather truncated posterior margin ( Delorme 1968 ), producing a lateral outline quite different to that of Arctocypris edita n. sp. Arctocypris edita n. sp. was found in shallow waters of ponds and the littoral zone of a lake on either a sandy or muddy substrate, once with submergent macrophytes, at altitudes of 4191–4626 m ( Table 1 ).