Hansenocaris Itô, 1985

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 : 15

Genus Hansenocaris Itô, 1985

Descriptions of y-naupliar morphospecies (‘types’) from Okinawan shallow water

Brief descriptions are presented below for one morphospecies (Type A*) of planktotrophic y-nauplius and 34 lecithotrophic morphospecies with alphabetical designations that match those used by Dreyer et al. (2023a) for the same putative taxa, with some additions. The planktotroph is included to facilitate the separation of planktotrophic and lecithotrophic y-nauplii from each other as the first step in using the identification key that follows the descriptions. To facilitate comparisons, the descriptions normally present similar types of information in the following order for last-stage nauplii (LSN): 1) general features; 2) length:width ratio; 3) shape in ventral view; 4) shape in lateral view; 5) measurements of length, width and thickness; 6) features of the labrum; and 7) features of the caudal end. The following features of the developing cyprids within the LSN cuticle are also mentioned: 1) coloration; 2) condition of yolk granules (if any); 3) distribution of marginal lipid vesicles (if any); and 4) features of the telson. The descriptions are accompanied by detailed figures ( Figs 6–19 ) to facilitate identification using the key. The lecithotrophs include three formally described species— Hansenocaris demodex , H. cristalabri and H. aquila (Olesen et al. 2022; Olesen & Grygier 2022)—and 31 undescribed morphospecies, a few of which were given ‘nicknames’ in earlier literature and some of which probably represent more than one species according to recent molecular systematic data ( Dreyer et al. 2023a). Further treatment of the other kinds of planktotrophic y-nauplii shown in Fig. 2C is postponed. Examples of live video of most of the y-naupliar morphospecies can be seen at https://youtu.be/er0mYLswV-c and are also deposited at Figshare.com: https://doi.org/10.6084/m9.figshare.24953568.v1.

Figures

Fig. 6. Last-stage nauplii of two different (morpho)species of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–F. Hansenocaris demodex Olesen et al., 2022 (all paratypes). G–L. Type C (‘Bumblebee’). Shown either in life (A–B, G–H) or as slide-mounted exuviae (C–F, I –L).Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 7. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–G. Type D* (“Big brown”). H–M. Type B. Shown either in life (A–B, H–J) or as slide-mounted exuviae (C–G, K–M). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 8. Last-stage nauplii of three different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–D. Type F. E–G. Type G. H–J. Type H. Shown either in life (A–B, E–F, H–I) or as slide-mounted exuviae (C–D, G, J). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 9. Last-stage nauplii of four different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–C. Hansenocaris cristalabri Olesen & Grygier, 2022. D–E. Hansenocaris aquila Olesen & Grygier, 2022. F–H. Y-nauplius Type AC. I–N. Y-nauplius Type AH*. Shown either in life (A–B, F–H, I–J), as slide-mounted exuviae (D–E, K–N) or in SEM (C). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible. A–E from Olesen & Grygier (2022).

Fig. 10. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–F. Y-nauplius Type E*. G–K. Y-nauplius Type AG*. Shown either in life (A–B, G–H) or as slide-mounted exuviae (C–F, I–K). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 11. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–G. Y-nauplius Type W. H–M. Y-nauplius Type AD. Shown either in life (A–C, H–J) or as slide-mounted exuviae (D–G, K–M). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 12. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–D. Y-nauplius Type U*. E–G. Y-nauplius Type V. Shown either in life (A, E–G) or as slide-mounted exuviae (B–D). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 13. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–E. Y-nauplius Type X. F–J. Y-nauplius Type K. Shown either in life (A–B, F–H) or as slide-mounted exuviae (C–E, I–J). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 14. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–F. Y-nauplius Type M. G–L. Y-nauplius Type AI. Shown either in life (A–B, G–I) or as slide-mounted exuviae (C–F, J–L). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 15. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–F. Y-nauplius Type L. G–M. Y-nauplius Type AB. Shown either in life (A–C, G–J) or as slide-mounted exuviae (D–F, K–M). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 16. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–E. Y-nauplius Type Y. F–J. Y-nauplius Type O*. Shown either in life (A, F–G) or as slide-mounted exuviae (B–E, H–J). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 17. Last-stage nauplii of three different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–E. Y-nauplius Type AF. F–K. Y-nauplius Type N*. L. Y-nauplius Type AP. Shown either in life (A–C, F–G) or as slide-mounted exuviae (D–E, H–L). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible. L from Grygier et al. (2019).

Fig. 18. Last-stage nauplii of two different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–F. Y-nauplius Type AL. G–J. Y-nauplius Type AJ. Shown either in life (A–C, G–J) or as slide-mounted exuviae (D–F). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 19. Last-stage nauplii of four different morphospecies of y-larvae (Facetotecta) from Sesoko Island (Okinawa, Japan). A–E. Y-nauplius Type AK. F–G. Y-nauplius Type AO. H. Y-nauplius Type AM. I–K. Y-nauplius Type AN. Shown either in life (A–B, H) or as slide-mounted exuviae (C–G, I–K). Abbreviations: A1 = first antenna; A2 = second antenna; Md = mandible.

Fig. 2. Y-naupliar (Facetotecta) diversity at Sesoko Island (Okinawa, Japan). A. Schematic life cycle of y-larvae (modified from Itô 1991; Glenner et al. 2008). B. Overview of 34 morphospecies of lecithotrophic last-stage y-nauplii obtained by laboratory rearing of earlier-stage nauplii collected in the plankton; three of them represent formally described species while 31 remain undescribed. C. Nine types of planktotrophic y-larvae, of which only Type A* is treated in detail in this paper. All photos in B and C are to the same scale. Figure also used in Olesen (2004). Examples of live video of most of the y-naupliar morphospecies can be seen at https://youtu.be/er0mYLswV-c and are also deposited at Figshare.com: https://doi.org/10.6084/m9.figshare.24953568.v1.