Hansenocaris undetermined

Olesen, Jørgen & Grygier, Mark J., 2024, Taxonomic diversity of marine planktonic ‘ y-larvae’ (Crustacea: Facetotecta) from a coral reef hotspot locality (Japan, Okinawa), with a key to y-nauplii, European Journal of Taxonomy 929 (1), pp. 1-90 : 28

publication ID

https://doi.org/ 10.5852/ejt.2024.929.2479

publication LSID

lsid:zoobank.org:pub:832192E7-A85A-4971-BA2F-D7420D299E8D

DOI

https://doi.org/10.5281/zenodo.10988680

persistent identifier

https://treatment.plazi.org/id/6515E623-0A2C-1E1E-39AA-6647FCCE97AE

treatment provided by

Plazi

scientific name

Hansenocaris undetermined
status

 

Y-nauplius Type E*

Figs 2 View Fig , 10A–F View Fig

Hansenocaris sp. – Itô 1991: 57, fig. 1 (see the ‘ Itô’s (1991) y-nauplius’ portion of the Discussion below).

Nauplius of undescribed lecithotrophic y-larva – Grygier et al. 2019: 1226–1228, figs 2c–h, 3a–b.

Type E* – Dreyer et al. 2023a: figs 4, 5a, c, tables s1–s2.

Material examined

JAPAN – Okinawa, Sesoko I. , laboratory pier, 26°38ʹ09.4ʺ N, 127°51ʹ55.2ʺ E • 9 LSN; 1991–2005 GoogleMaps 40 LSN, 29 of which molted to cyprids; 2018–2019 ( Tables 1 and S1 View Table 1 ).

Description

LAST-STAGE NAUPLIUS (LSN). Lecithotrophic. Body short-handled spoon-shaped in dorso-ventral view; about 1.5 times as long as wide; cephalic shield widely ovate, with sharp discontinuity in body outline leading into trunk. In lateral view, trunk axis bent downwards 50–60° with respect to cephalic axis. Length 210–260 µm (without dorso-caudal spine), greatest width 140–150 µm, greatest dorso-ventral thickness ca 80 µm. Labrum with pentagonal outline in ventral view; free posterior margin extending into 10 µm long median spine; surface divided into facets by cuticular ridges; pores not examined in detail, but at least with pair of postero-lateral pores. Caudal end attenuate, terminating in 40–50 µm long, often slightly curved dorso-caudal spine upturned 50° with respect to trunk axis and armed with spiny ornamentation and accompanied ventrally at base by pair of ca 7 µm long furcal spines.

CYPRID VIEWED THROUGH CUTICLE OF LSN. Body weakly brownish-pigmented. Cephalon with one or two pairs of distinct yolk/lipid vesicles close to its anterior margin. Gut-like central tube often with brownish/reddish-colored yolk granules, especially in posterior part. Telson about as long as wide and less than half as long as thorax.

Identification and variation

Recognizable by the combination of its general body shape, pentagonal labral outline, relative slender and often curved dorso-caudal spine, and the pair of distinct yolk granules/vesicles at the anterior margin of the cephalic shield. Little morphological variation is seen between specimens. Molecular diversity revealed by sequencing 15 specimens ( Dreyer et al. 2023a) suggests that this naupliar morphospecies includes two or three distinct species.

Distribution

Japan (Sesoko Island, Okinawa; Tanabe Bay, Wakayama).

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