Amblyopsoides O.S. Tattersall, 1955

Wittmann, Karl J., 2024, The Mysidae (Crustacea, Mysida) of the ANDEEP I-III expeditions to the Antarctic deep sea with the description of twelve new species, establishment of four new genera and with world-wide keys to the species of Erythropinae and Mysidellinae, European Journal of Taxonomy 940, pp. 1-180 : 59-60

Genus Amblyopsoides O.S. Tattersall, 1955

Amblyopsoides O.S. Tattersall, 1955: 108 (description of type species).

Amblyops – Birstein & Tchindonova 1970: 284 (claimed as senior synonym of Amblyopsoides ).

Amblyopsoides – Birstein & Tchindonova 1970: 284 (in synonymy, not acknowledged). — Mauchline 1980: 27 (in key to genera). — Murano 1999: 1118 (in catalog). — Wittmann et al. 2014: 336 (taxonomy). — Hernández-Payán & Hendrickx 2020: table 1 (species numbers, diagnostic characters of species).

Type species

Amblyopsoides obtusa O.S. Tattersall, 1955 , by original designation according to ICZN (1999).

Diagnosis

Based on adults of both sexes. Carapace normal. Eye rudiments immotile, without stalks, closely set though not fused, not connected by membranous integument, lateral margins not produced in a non-sensory finger-like process; dorsal face with ocular papilla, eyes without any or with reduced ommatidia. Antennal peduncle with three segments lined in same plane. Antennal scale extends beyond antennular trunk. Scale with small apical segment in most species; mesial margin setose, lateral margin bare up to a large disto-lateral tooth at> ¼ of scale length from apex. Thoracomeres and pleomeres normal. Thoracic endopods 1–8 not prehensile. Endopods 3–8, as far as known, with unsegmented carpus separated from 1–2-segmented propodus by an oblique articulation. Female, as far as known, with three pairs of well-developed oostegites. Penes well developed, bearing some setae. Male pleopods, as far as known, biramous, setose, no spines; no modified setae; exopods multi-segmented; endopod 1 unsegmented, endopods 2–5 multi-segmented. Female pleopods reduced to uniramous setose plates. Well-developed pseudobranchial lobe in both sexes. Both rami of uropods unsegmented, setose all around; endopod with 0–1 spine on mesial margin below statocyst. Telson trapezoid, without or with mid-terminal indentation, lateral margins not serrated, no lateral constriction. Proximal third to half of lateral margins bare, remaining distal portion with spines. Terminal margin with spines and mostly a pair of paramedian setae (only setae bases preserved in Fig. 36F ).

New combination

Amblyopsoides laticauda ( Birstein & Tchindonova, 1958) comb. nov. is here recombined from Dactylamblyops laticauda Birstein & Tchindonova, 1958 , based on the structure of the antennal scale (as in Fig. 33D ), telson (as in Fig. 38E ) and eyes. Attempts to borrow the types have failed. The design of the eyes in Birstein & Tchindonova (1958: fig. 28) may allege a differentiation in eyestalk and cornea, but the text clearly indicates that “The visual elements are concentrated in the basal part of the eye, particularly densely close to the basis, and disappear gradually towards the end” [translation]. Accordingly, there is no clear differentiation of an eyestalk. In addition, the eyes are dorsally flattened. In conclusion, eye structure together with the long setose lobe of the antennal scale (and less importantly also the telson structure) fit into Amblyopsoides and disprove Dactylamblyops .

Species included

– A. crozetii (G.O. Sars, 1883) from the Southern Ocean: Kerguelen and Crozet Islands, off East Antarctica, 45– 68° S, 48– 70° E and 25– 60° W, depth 800–2960 m (G.O. Sars 1884, 1885; Petryashov 2006; San Vicente 2010; see also ‘Discussion’: 133); records from the Arctic doubted by Brattegard & Meland (1997) and Hernández-Payán & Hendrickx (2020)

– A. fenestragothica sp. nov. from the Southern Ocean: Drake Passage and NW Weddell Sea, 61– 65° S, 53– 54° W, depth 2086–2894 m

– A. halleyi Ledoyer, 1990 from the Southern Ocean: Bellingshausen Sea, Weddell Sea and off Kerguelen Islands, 47– 74° S, 65° W – 66° E, depth 585–1223 m ( Ledoyer 1990, 1995; Brandt et al. 1998; San Vicente 2010)

– A. laticauda ( Birstein & Tchindonova, 1958) comb. nov. from the NW Pacific: Kurile-Kamchatka Trench, 49° N, 159° E, depth 4500 m ( Birstein & Tchindonova 1958)

– A. lepidophthalma sp. nov. from the Southern Ocean: South Sandwich Trench and Drake Passage, 58– 59° S, 25– 60° W, depth 2281–2375 m

– A. obtusa O.S. Tattersall, 1955 from the SW Atlantic: Strait of Magellan, Patagonian shelf SW of Falkland Islands ( Malvinas), 51– 55° S, 62– 69° W, depth 265–534 m (O.S. Tattersall 1955; Brandt et al. 1998, 1999)

– A. ohlinii (W.M. Tattersall, 1951) from the N Atlantic (40– 73° N, 15– 70° W) and N Pacific (39– 44° N, 143– 149° E and 31° N, 117° W), total depth range 1709–2265 m (W.M. Tattersall 1951; Fukuoka 2009; Hernández-Payán & Hendrickx 2020)

Figures

Fig. 36. Telson in Amblyopsoides fenestragothica sp. nov., holotype, immature male with BL of 16.2 mm (ZMH 64660). A. Telson expanded on slide, dorsal view. B. Detail of A, showing scale fields close to lateral margin of telson. C. Detail of A, showing basal portion of telson with two pore fields. D. Detail of C, showing part of left pore field (some pores not in focus). E. Detail of A, showing ventral anal lobe, focused through the artificially transparent tissue, dorsal view. F. Detail of A, showing distal portion of telson. Abbreviations: al = anal lobe; an = anus; lf = mid-longitudinal fold; pf = pore fields. A. Object artificially separated from background.

Fig. 33. Amblyopsoides fenestragothica sp. nov., holotype, immature male with BL of 16.2 mm (ZMH 64660). A. Carapace with eyes expanded on slide, dorsal view, arrows point to minute pore group (detail in Fig. 31D). B. Antennula, dorsal view. C. Detail of B, showing disto-median lobe of antennular trunk. D. Antenna with antennal gland, ventral view, setae omitted from antennal scale. E. Mandible with right palpus, caudal view. F. Masticatory part of right mandible, caudal view. G. Masticatory part of left mandible, rostral view. H. Maxillula, caudal view. I. Maxilla, caudal view.

Fig. 38. Amblyopsoides lepidophthalma sp. nov., paratype, subadult female with BL of 24.4 mm (A–F: ZMH 64663) and holotype, subadult male 21.4 mm (G: ZMH 64662). A. Left eye rudiment with ocular papilla (op), dorsal view. B. Detail of A, showing tip of ocular papilla with toroidal bulge (tb). C. Detail of A, showing scales on anterior margin of eye, tangential view. D. Detail of A, showing scales on dorsal face of eye rudiment. E. Telson, dorsal view. F. Detail of E, showing left pore field and mid-longitudinal fold. G. Terminus of telson in another specimen, dorsal view. Abbreviations: lf = mid-longitudinal fold; pf = pore field. A–F. Objects expanded on slide with dorsal face upwards. G. Object photographed in loco. A–B, E, G. Objects artificially separated from background.