TAILIEUCHUNG - Reconsideration of ontogenetic changes of the maxillula in the species of Genus loxoconcha sars, 1866 (crustacea, ostracoda, podocopida)
In previous study, it was shown that the general development and number of setae on the maxillula are identical between the two species (L. noharai Le & Tsukagoshi, 2014 and L. japonica Ishizaki, 1968) of this genus from the second (A-7) to the fourth instars (A-5), and the differences between the two species appear in and after the fifth instar (A-4). | Tạp chí Khoa học công nghệ và Thực phẩm 16 (1) (2018) 21-29 RECONSIDERATION OF ONTOGENETIC CHANGES OF THE MAXILLULA IN THE SPECIES OF GENUS LOXOCONCHA SARS, 1866 (CRUSTACEA, OSTRACODA, PODOCOPIDA) Le Doan Dung*, Nguyen Thi Phuong Ho Chi Minh City University of Food Industry *Email: dungld@ Received: 15 June 2018; Accepted for publication: 30 August 2018 ABSTRACT Ostracod maxillula is the fourth head appendage and it is the one of key indicators in taxonomy, phylogeny and evolution. So far, some reports on ontogenetic changes of the maxillula of the genus Loxoconcha have been already published. In previous study, it was shown that the general development and number of setae on the maxillula are identical between the two species (L. noharai Le & Tsukagoshi, 2014 and L. japonica Ishizaki, 1968) of this genus from the second (A-7) to the fourth instars (A-5), and the differences between the two species appear in and after the fifth instar (A-4). In the present report, by observation of the maxillulan ontogenetic changes in Loxoconcha sesokoensis Le & Tsukagoshi, 2014, the differences in the general development and number of setae among three Loxoconcha species (., L. noharai Le & Tsukagoshi, 2014; L. japonica Ishizaki, 1968 and L. sesokoensis Le & Tsukagoshi, 2014) can be found at the earlier instar, the fourth instar (A-5). This finding contributes to the more accurate understanding of ontogenetic changes of maxillula and the phylogeny in the genus Loxoconcha. Keywords: Loxoconcha, chaetotaxy, maxillula, taxonomy, phylogeny. 1. INTRODUCTION The genus Loxoconcha was established by Sars in 1866 [1]. It is one of the most diverse recent ostracod genera. Species of this genus are widely distributed in low-to-middle-latitude areas of marine and brackish waters and up to more than 150 living and 350 fossil species have been identified in the world [2]. The history of this genus is being debated. So far, this genus is considered to originate in the late .
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