Four new species of the interstitial family Cobanocytheridae (Crustacea: Ostracoda) from central Japan

Abstract

Four interstitial cobanocytherid species are described from central Japan: Cobanocythere ikeyai sp. nov., Cobanocythere lata sp. nov., Paracobanocythere watanabei sp. nov. and Paracobanocythere grandis sp. nov. The reports of the two new Paracobanocythere species are the second and third for this genus since the original description of P. hawaiiensis Gottwald, 1983. Cobanocythere ikeyai sp. nov., and C. lata sp. nov., from Japan are morphologically more similar to the species of the “lanceolata group” by Gottwald (1983) and C. guttaeformis Gottwald, 1983 from the Galapagos Islands, respectively, rather than to other Cobanocythere species from Japan. The Japanese archipelago (eastern Eurasian Continent) and the Galapagos Islands (north-western South America) are separated by about 15,000 km from each other, and have never been adjoined throughout geological history. This fact, and also the morphological similarities between Cobanocythere species from Japan and the Galapagos Islands, suggests that this genus may have undergone global dispersal at several times in the past. Conversely, the genera Cobanocythere and Paracobanocythere are distributed not only around continents and continental islands but also around oceanic islands such as the Hawaiian and Galapagos Islands. We conclude, therefore, that the cobanocytherids seem to have been able to disperse long distances across oceans.

Two new species of the interstitial genus Parvocythere (Crustacea, Ostracoda, Cytheroidea) from Japan: an example of morphological variation

“…The reductive distal claw therefore appears only in the species of Group N, and the degree of reduction is varied. The interstitial cobanocytherid species also have one claw and one seta on the distal end of the antenna ( Hartmann 1959 , Schornikov 1975 , Gottwald 1983 , Higashi and Tsukagoshi 2011 ). The reductive antennal distal claw is probably a character status related to the adaptation to the interstitial environment.…”

A new interstitial ostracod species of the genus Paracobanocythere from Vietnam, with mitochondrial CO1 sequence data of three Asian species

“…The specimens of both Paracobanocythere grandis and Paracobanocythere watanabei used in DNA extractions were collected from the type localities (See Higashi and Tsukagoshi 2011, fig. 1): Mochimune Beach (34°55'04"N, 138°21'43"E), Shizuoka, central Japan, on 1 Aug. 2015 and Oura Beach (34°40'05"N, 138°56'28"E), Shizuoka, central Japan, on 30 Sep. 2012.…”

“…n. are easily distinguishable by the length of carapace (Table 3). While Paracobanocythere grandis has an exceptionally large carapace (approximately 500 µm) for this genus (Higashi and Tsukagoshi 2011), those of the other three species are relatively smaller (roughly 300 µm) (Gottwald 1983, Higashi and Tsukagoshi 2011). Furthermore, the female carapace larger than that of the male in Paracobanocythere grandis , and that is opposite to the status in the other three species (Table 3).…”

“…The new species belongs to the genus Paracobanocythere , which shows typical features of interstitial taxa, including a small and dorso-ventrally depressed carapace inhabiting the interstices between grains of coarse sand (Gottwald 1983, Hartmann 1991, Higashi and Tsukagoshi 2011). Thus far, three species of this genus have been described; these include Paracobanocythere hawaiiensis Gottwald, 1983 (type species), from the island of O’ahu in Hawaii, as well as Paracobanocythere grandis Higashi & Tsukagoshi, 2011 and Paracobanocythere watanabei Higashi & Tsukagoshi, 2011, from the sand beach in Shizuoka Prefecture, on the Pacific coast of central Japan.…”