Mysidetini Holt & Tattersall, 1906

Daneliya, Mikhail E., 2023, On the Mysid Crustacean Genus Deltamysis (Mysidae: Heteromysinae), with a New Species and a New Record from Australia, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 413-430 : 414-415

Mysidetini Holt & Tattersall, 1906

Mysidetinae Holt & W. M. Tattersall, 1906: 39.—W. M. Tattersall, 1908: 32.—Zimmer, 1909: 45, 46, 139.

Mysidetini .—Wittmann et al., 2014: 341.—Wittmann & Wirtz, 2017: 147.—Wittmann & Ariani, 2019: 5.— Daneliya, 2021: 5, 6, 46.—Scripter et al., 2020: 504.— Kou et al., 2020: 3.

Type genus. Mysidetes Holt & Tattersall, 1906 , by monotypy.

Diagnosis. Pereopod 1 endopod not differentiated from pereopod 2 endopod, not prehensile, with multisegmented carpopropodus. All pleopods reduced to simple plates in both sexes.

Comparison. Mysidetini is distinguished from other heteromysine tribes by the multisegmented carpopropodus of the pereopod 1 (at least 3-segmented). From the tribe Heteromysini it also differs by the similarity of the pereopods 1 and 2. In Heteromysini , the pereopod 1 endopod is prehensile and 2-segmented (except in Platyops stenoura [ Hanamura & Kase, 2004], in which it is 3-segmented), and pereopod 2 endopod is normal, multisegmented. An additional feature separates Mysidetini from Harmelinellini : the rudimentary nature of all pleopods in both sexes. In Harmelinellini , the male pleopod 3 is uniquely long and 2-segmented.

Remarks. Originally, this taxon was designated as a subfamily within Mysidae (Holt & W. M. Tattersall, 1906) for a single genus Mysidetes Holt & Tattersall, 1906 . Closely resembling Mysidellinae Czerniavsky, 1882 and Heteromysinae in the antennal scale, pleopods, and telson, Mysidetinae Holt & Tattersall, 1906 was distinguished from the two mentioned subfamilies by the structure of the maxilliped 1 (termed as “maxillipede” or “first thoracic limb”) and the pereopod 1, respectively, and from Leptomysinae only by the reduced pleopods in both sexes. The characters proposed by Holt & W. M. Tattersall (1906) and Zimmer (1909) were not sufficiently diagnostic to maintain separate status of the subfamily ( Hansen, 1910, 1913). In a century, Wittmann et al. (2014) re-established the taxon in the status of a tribe within Heteromysinae and included eight genera: Bermudamysis Băcescu & Iliffe, 1986 , Burrimysis Jaume & Garcia, 1993 , Deltamysis , Kochimysis , Mysidetes , Mysifaun Wittmann, 1996 , Platyops Băcescu & Iliffe, 1986 , and Pseudomysidetes W. M. Tattersall, 1936 . All members of Mysidetini shared normal, not prehensile pereopods with the multisegmented carpopropodus, the rudimentary, non-modified and non-dimorphic pleopods, and the telson lateral margins with spiniform setae in the distal part only. Certain species of Mysidetes have the telson lateral spiniform setae along the entire length ( M. dimorpha O. S. Tattersall, 1955 , M. hanseni Zimmer, 1914 , M. microps O. S. Tattersall, 1955 , M. morbihanensis Ledoyer, 1995 , and M. posthon Holt & W. M. Tattersall, 1906 ) or separated by a gap ( M. antarctica O. S. Tattersall, 1965 , and M. crassa Hansen, 1913 ), which means that this character is not suitable for the diagnosis.

In composing the new diagnosis, I exclude all variable characters, including the size of the male process on the antennulae, the number of the oostegites, the shape of the penes and the telson. In the previous work ( Daneliya, 2021), I revised the diagnosis of Heteromysini and transferred Platyops and Bermudamysis into the redefined tribe. However, I did not provide a revised diagnosis of Mysidetini , which is specifically done here.

Composition. The tribe Mysidetini contains five genera: Burrimysis , Deltamysis , Mysidetes , Mysifaun , and Pseudomysidetes .