Platyops Băcescu et Iliffe, 1986

Daneliya, Mikhail E., 2021, On the Mysid Crustacean Genus Heteromysis (Mysidae: Heteromysinae) of the Tasman Sea, with Notes on the Tribe Heteromysini, Records of the Australian Museum (Rec. Aust. Mus.) 73 (1), pp. 1-50 : 45-46

Platyops Băcescu et Iliffe, 1986

Platyops Băcescu et Iliffe, 1986: 100 , 102.— Müller, 1993: 211.— Nouvel et al., 1999: 79.— San Vicente & Monniot, 2014: 333, 334, 341.— Wittmann et al., 2014: 341.

Type species. Platyops sterreri Băcescu et Iliffe, 1986 , by monotypy.

Diagnosis. Telson narrowly trapezoidal (nearly triangular), apically truncated, without cleft, bearing rather long spiniform setae. Eyes with distomedial spine directed forward; eye cornea shifted to lateral side; eyestalk without distolateral lobe. Segment 3 of antennular peduncle with thin distomedial setae, not directed backwards. Pereopod 2 carpopropodus multisegmented. Pereopods 3−6 preischium without process; ischium without flagellated spiniform setae. Uropodal endopod without spiniform setae.

Comparison. The most characteristic feature of this genus is the eye structure, particularly the presence of a strong anterior spine, directed forward. A spine on the eyestalk is found in certain members of Heteromysis , but the direction of the spine is unique. This is the only genus in the tribe, in which the telson cleft is missing. Platyops does not seem to be particularly close to any other genus of Heteromysini . At the same time it has all the characters of the tribe: pereopod 1 endopod is differentiated from the pereopod 2 endopod, prehensile (in P. dennisi and P. sterreri [ Băcescu et Iliffe, 1986]), with 2-segmented carpopropodus (uniquely 3-segmented only in P. stenoura comb. nov., see below), pereopod 2 endopod is differentiated from pereopods 3−6, and other features.

Remarks. Băcescu & Iliffe (1986) remarked that Platyops was convergent with Heteromysoides , which was indeed a manifestation that the genus is related to the heteromysine genera. Original placement of Platyops in Mysini caused it to be missing among the heteromysine genera in subsequent works, before Nouvel et al. (1999) finally placed in within Heteromysini . Probably by a mistake it was mentioned as a part of the subfamily Leptomysinae ( San Vicente & Monniot, 2014). However, because of the weekly prehensile nature of pereopod 1 endopod in the type species, it found its position in the heteromysine tribe Mysidetini ( Wittmann et al., 2014) . With the renewed concept of Heteromysini , I revise here the position of Platyops and transfer it to this tribe.

Composition. Three species are included into Platyops : Platyops dennisi ( Bowman, 1985) comb. nov., Platyops simplex (Hanamura et Kase, 2001) comb. nov. (formerly Heteromysoides ), Platyops stenoura ( Hanamura et Kase, 2004) comb. nov. (formerly Heteromysoides ) and P. sterreri .