A new bathyal mysid of the family Petalophthalmidae (Crustacea: Mysida) <br />from the Bismarck Sea (Western Tropical Pacific Ocean)

Abstract

A new species of the genus Petalophthalmus (Crustacea: Mysida: Petalophthalmidae) is described, based on one specimen collected from the Bismarck Sea (Papua New Guinea, Western Pacific Ocean). This species can be distinguished from the other species of the genus Petalophthalmus by the globular cornea and the armature of the telson. This new species lives between 800 and 1065 m depth. A discussion on the geographic and bathymetric distribution and an identification key to world species of Petalophthalmus are provided.

Lophogastrida and Mysida (Crustacea) of the “DIVA-1” deep-sea expedition to the Angola Basin (SE-Atlantic)

“…Reduction of the lacinia mobilis on one of the two mandibles is also found in at least nine bathyal to abyssal species of the genera Hansenomysis Stebbing, 1893, Bacescomysis Murano & Krygier, 1985, Petalophthalmus and Ipirophthalmus gen. nov. These three genera belong to the Petalophthalmidae and are morphologically remote from Abyssomysis gen. nov. and Mysimenzies Băcescu, 1971. In the respective species of Petalophthalmidae, the lacinia mobilis of the left or the right mandible is reduced to varying degrees (Birstein & Tchindonova 1958;Băcescu 1971aBăcescu , 1971bSan Vicente & Corbari 2015;present study). Based on the strong setation of perioral structures Băcescu (1971b) argued that Hansenomysis species are detritus feeders.…”

“…These legs were reported as being different in the remaining two species here also assigned to Ipirophthalmus gen. nov.: Pillai (1968) reported an elongate endopod 4 ending in a brush of setae upon redescription of P. oculatus (now I. oculatus) based on a single specimen. San Vicente & Corbari (2015), however, concluded that Pillai (1968) may have confounded endopod 5 with endopod 4, due to the habitus of this specimen illustrated by Pillai (1968: fig. 1) with thoracopods 3-4 broken.…”

“…San Vicente, Frutos & Cartes, 2014 differs, according to its first description, from the new species by a small, acute tooth behind anterior margin of carapace, no rostrum developed; outer flagellum of antennular peduncle without subbasal ridge; antennal flagellum with fewer (5) segments in females; pars centralis of right mandible without digitus; distal segment of maxillula with few (7) serrated spines; claw of thoracic endopods 1-2 fused with dactylus; coxa of endopod 1 without endite; merus of endopod 2 with smooth outer margin, carpopropodus without barbed setae apart from the usual smooth setae; flagellum of exopods 3-4 with more segments (19-20); European Journal of Taxonomy 628: 1-43 (2020) endopod 8 shorter than exopod; endopod of uropods not extending beyond telson; basal segment of exopod with three spines but no barbed seta on disto-lateral corner. San Vicente & Corbari, 2015, differs according to its first description, from the new species by the presence of some scattered visual elements in the globular cornea; small, acute tooth behind anterior margin of carapace, no rostrum developed; outer flagellum of antennula without subbasal ridge; antennal flagellum of female with more (7) segments; processus molaris of right mandible not trilobate; distal segment of maxillula with fewer (7) serrated spines; coxa of thoracic endopod 1 without endite; carpopropodus of endopod 2 without barbed setae apart from the usual smooth setae; endopod 5 without apical claw, terminal margin of propodus armed with two short cuspidate setae in addition to the pair of microserrated setae, the latter as in Fig. 3D; flagellum of thoracic exopods with few segments: exopods 3-4 with 13-15, exopod 5 with 16, exopods 6-8 with 13-16; female pleopod 1 unsegmented; female pleopods 1-4 (possibly also no.…”