Amblyops bipapillatus, Wittmann, 2024

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 : 41-49

publication ID	https://doi.org/ 10.5852/ejt.2024.940.2577
publication LSID	lsid:zoobank.org:pub:19DE5E4F-3A2C-41FF-A593-A4C74F7A9ABD
DOI	https://doi.org/10.5281/zenodo.12206512
persistent identifier	https://treatment.plazi.org/id/D3C59570-163A-4707-A043-F889EA94456A
taxon LSID	lsid:zoobank.org:act:D3C59570-163A-4707-A043-F889EA94456A
treatment provided by	Plazi
scientific name	Amblyops bipapillatus
status	sp. nov.

Treatment

Amblyops bipapillatus sp. nov.

urn:lsid:zoobank.org:act:D3C59570-163A-4707-A043-F889EA94456A

Figs 20–24 View Fig View Fig View Fig View Fig View Fig

Diagnosis

Based on adult female. Fitting within ranges of generic diagnosis. Carapace with broadly rounded anterior margin. Eye rudiments with complex structure ( Figs 20 View Fig , 21A View Fig ), no visual elements; eyes converging mesially, dorsoventrally compressed by a factor of 1.3–1.5. Each eye rudiment with two basally wide ocular papillae; length of distal papilla 28–31% of length of antero-posterior extension of eye rudiment, proximal papilla 21–26%. Distal papilla mid-rostrally forming part of anterior margin, and proximal papilla at distal third from mesial margin. Disto-lateral edge of antennal sympod produced into one large tooth. Antennal scale with setose mesial margin and bare lateral margin up to remaining, available scale length (apex broken). Mouthparts normal, labrum rostrally rounded. Thoracic exopod 1 with 9-segmented flagellum, exopods 4–8 with 10-segmented flagellum (exopods 2–3 broken). Three carpopropodus segments separated from each other by oblique articulations in thoracic endopods 5 and 8 (endopods 3–4 and 6–7 broken). Female with three pairs of oostegites contributing to outer wall of marsupium, first pair small but functional. Endopod of uropods with one minute spine on mesial margin below statocyst. Telson linguiform, distal half subtriangular with nearly continuously converging lateral margins, narrow terminal margin flattened; telson length 2.2 times maximum width. Lateral margins proximally bare, their distal 4/7 armed with 29–32 normal-shaped spines, distally gradually increasing in size; terminal margin with small median spine flanked by slightly subterminally inserting pair of setae, in turn flanked by two pairs of large spines, among which submedian spines largest, only ≈ 1/15 of telson length. Telson with total of ≈ 66 spines and two setae.

Etymology

The species name is an adjective with masculine ending, formed by amalgamation of the Classic Latin adverb ‘ bis ’ (‘twice’) with the adjective ‘ papillatus ’ (‘papillary’), referring to the pair of papillae on each eye rudiment ( Fig. 20A–C View Fig ).

Material examined

Holotype SOUTHERN OCEAN • 1 ♀ ad. (BL = 16.7 mm, on slides); eastern Weddell Slope , Kapp Norvegia, ANDEEP-III station 080-9; 70°39.07ʹ S, 14°43.36ʹ W to 70°39.22ʹ S, 14°43.39ʹ W; depth 3103– 3102 m; 23 Feb. 2005; EBS epinet; ZMH 64659 View Materials . GoogleMaps

Other material

SOUTHERN OCEAN • 1 juv. (BL = 5.8 mm, in 2 parts); Powell Basin, SW continental slope of South Orkney Islands, ANDEEP-III station 151-7; 61°45.52ʹ S, 47°07.68ʹ W to 61°45.42ʹ S, 47°08.04ʹ W; depth 1182–1185 m; 21 Mar. 2005; EBS epinet GoogleMaps .

Type locality and distribution

The type locality is ANDEEP III station 080-9: eastern Weddell Slope, Kapp Norvegia, SW of Wegener Canyon, 70°39.07ʹ S, 14°43.36ʹ W to 70°39.22ʹ S, 14°43.39ʹ W, depth 3103– 3102 m. Also found in the Powell Basin. Total range 62– 71° S, 15– 47° W, depth 1182–3103 m.

Description

Holotype (♀)

All features as in specific diagnosis. Adult female with empty marsupium, BL = 16.7 mm. Carapace measures 31% of BL, cephalothorax 36%, pleon without telson 48% and telson 16%. Small, distally rectangular subrostral process extends shortly beyond anterior margin of carapace. Clypeus with short median projection anteriorly, not reaching half-length of basal segment of antennular trunk ( Fig. 21A View Fig ).

CARAPACE ( Figs 20E View Fig , 21A View Fig ). Normal, cervical sulcus strong, no cardial sulcus visible; disto-lateral edges rounded; posterior margin concave, terminal indentation shallow, broadly rounded. Carapace leaves 1½ thoracomeres mid-dorsally exposed. No pores detected (though not excluded). Large parts of carapace indicated as shadowed areas in Fig. 21A View Fig covered by roughly ellipsoidal cuticular structures ( Fig. 20E View Fig ), representing minute depressions in part (accidentally) filled with external material.

EYES ( Figs 20A–D View Fig , 21A View Fig ). Antero-posterior extension of eye rudiments 0.8 of maximum width and about as long as terminal segment of antennular trunk. Organ of Bellonci near distal papilla. Rudiments with smooth cuticle all around except for pore at tip of ocular papillae and slender tooth-like scales ( Fig. 20D View Fig ) along mesially declining diagonal margin which separates thicker proximo-lateral portion from disto-mesial portion of eye rudiment; no other scales on eye rudiments.

ANTENNULA ( Fig. 21A View Fig ). Trunk measures 9% of BL. It extends ¾ of its length beyond eyes. Transverse articulation between three trunk segments. Measured along dorsal midline, basal segment 0.4 of trunk length, median 0.2 and terminal 0.4. Length of basal segment 0.7 times width. Basal segment produced in short lobe at disto-lateral edge, lobe apically with four setae; antennular bursa distinct, no ventral carina. Length of terminal segment 0.8 of width in dorsal view, 0.9 in ventral view. This segment with disto-median lobe armed with three small teeth increasing in size laterally, lobe disto-laterally with four barbed setae as in Fig. 4B View Fig ; no female lobe, no callynophore ( Fig. 21A View Fig ). Width of outer antennular flagellum measured near basis about same as width of inner flagellum.

ANTENNA ( Fig. 21A–B View Fig ). Sympod 2-segmented, caudally in addition with large end sac of antennal gland. Segments 1–4 contribute 27%, 12%, 18% and 42% to total length of peduncle in dorsal view, vs 28%, 28%, 13% and 31% in ventral view, respectively. Differences between dorsal and ventral views mainly reflect strongly oblique border between second segment and dorsally overlapping third segment. Tip of antennal scale broken in both available specimens.

MANDIBLES ( Fig. 21C–E View Fig ). Basal segment of palp contributes 9–10%, median segment 64–66% and apical segment 25–26% to total palp length. Median segment 2.4–2.6 times as long as wide, mesial and lateral margins convex, lateral margin bent mesially ( Fig. 21C View Fig ). Length of apical segment 3–4 times maximum width. Palp not hispid, its basal segment without setae, median segment densely setose along lateral and mesial margins, apical segment densely setose along mesial margin and only sparsely setose along lateral margin. Masticatory part of right mandible ( Fig. 21E View Fig ): pars incisiva with four large teeth; digitus mobilis serrated by numerous small teeth over most of its mesial margin, its disto-mesial edge extended into one large tooth. Pars centralis with eight acute, smooth spines: most ventral (= aboral) spine very large, these spines set apart dorsally (orally) followed by dense series of one small and six intermediate-sized spines. Processus molaris folded ventrally, bearing strong grinding lamellae proximally ending in teeth and dense bundle of stiff bristles on distal margin including proximal edge. Masticatory part of left mandible ( Fig. 21C–D View Fig ): pars incisiva with four large and several small teeth; digitus mobilis with four large teeth, pars centralis with six slender spines armed with stiff bristles; processus molaris with short grinding lamellae proximally not ending in teeth and with dense cover of stiff bristles on proximal (= oral) edge.

GUT ( Fig. 22 View Fig ). Foregut with normal gross structure. Lateralia with brushes of slender, proximally smooth, apically coronate spines ( Fig. 22B View Fig ) of various length and with slender, apically pronged spines ( Fig. 22C View Fig ), only latter type of spines densely coated with minute teeth along at least distal half of shaft. Posterior part of lateralia on each side with cluster of 11–12 spines armed with stiff bristles, peripheral spines larger than central spines ( Fig. 22D View Fig ). Dorsolateral infoldings on each side with cluster of two large spines at some distance mesially accompanied by 3–4 smaller spines, all these spines unilaterally serrated along distal third to half ( Fig. 22E View Fig ). Storage volume about half-filled with mainly masticated, unidentifiable organic materials (detritus) and abundant large mineral particles, plus remains of at least one copepod. Midgut with unidentified organic material and with many mineral particles, on average smaller than those of foregut. Anal lobe distinct (dashed lines in Fig. 24F View Fig ), weakly cuticularized.

MAXILLULA ( Fig. 21F View Fig ). Distal segment with eleven strong spines on transverse terminal margin, these spines unilaterally serrated mostly along median portions. This segment subterminally with three setae bearing long stiff barbs; no nearby pores detected. Endite of maxillula terminally with three large, distally spiny setae, on both sides accompanied by numerous less strong setae. Most proximal seta backward curved.

MAXILLA ( Fig. 21G View Fig ). Sympod with three mesial lobes, densely setose along their disto-mesial margins. Convex mesial portion of sympod may be interpreted as additional lobe bearing large, dense fan of setae. One large seta extends shortly beyond this fan, on caudal face, at margin near distally neighboring lobe; this seta apically and subapically with unilateral series of short, stiff barbs. Exopod of maxilla just barely not reaching terminal margin of basal segment of palp. Exopod with dense series of plumose setae all along lateral margin; largest seta at tip of exopod. Mesial margin bare. Maxillary palp with distal segment contributing ⅗ of palp length. This segment two times as long as maximum width; segment densely setose all along distal ⅔, no spines. Mesial margin of proximal segment with three normal-shaped barbed setae (below drawing plane in Fig. 21G View Fig , therefore visualized by dashed lines).

THORAX ( Fig. 23 View Fig ). Sternite 1 with distally rounded median lobe as normal in Mysidae . One large, basally thick, barbed seta closely accompanied by 2–4 smaller such setae (most parts below drawing plane, visualized by dashed lines in Fig. 23E View Fig ) on intersegmental joint between sternites 4–7 and respective sympods (sternites 2–3 and 8 damaged). Exopods 1 and 4–8 available, remaining exopods broken. Available basal plates with smooth cuticle, length twice maximum width, plates with minute tooth-like distal projection on disto-lateral edge, projection unapparent in Fig. 23A View Fig due to its small size. Epipod 1 leaf-like, about as long as combined ischium and merus of endopod 1; no seta. Endopods 1–2, 5 and 8 available, remaining endopods broken. Available endopods with smooth cuticle, not counting setae; no pores detected. Coxa of endopod 1with small mesial lobe apically bearing one small barbed seta; basis with large, setose endite, remaining segments without clear endite. Endopods 1–2 with six segments ( Fig. 23A, C View Fig ), endopods 5 and 8 with eight segments counting from basis to dactylus ( Fig. 23E View Fig ). Dactylus of endopod 2 reflexed ( Fig. 23C–D View Fig ). All available dactyli with basally wide, weakly curved acute nail; nails 5 and 8 short ( Fig. 23F, H View Fig ), nail 1 normal-sized ( Fig. 23B View Fig ), nail 2 longest ( Fig. 23D View Fig ); nails 1–2 and 5 smooth ( Fig. 23B, D, F View Fig ), nail 8 microserrated along distal fourth of its convex lateral (= outer) margin ( Fig. 23I View Fig ). Serration of outer rather than inner margin appears exceptional in Mysidae .

PLEON ( Fig. 24A–D View Fig ). Length of pleomeres 1–5 is 0.6, 0.6, 0.5, 0.5 and 0.6 times length of pleomere 6, respectively. Pleopods increasing in length caudally. Scutellum paracaudale subtriangular with weakly convex margins and blunt apex.

TAIL FAN ( Fig. 24E–H View Fig ). Uropods with smooth cuticle, not considering setae and single spine. Margins of endopod converge in narrow V-shaped manner up to blunt apex. Exopod with almost straight lateral margin and convex mesial margin; its terminus broadly rounded, convex. Exopod measures 1.3 times endopod length and also 1.3 times that of telson; endopod about as long as telson. Exopod extends 0.3 times its length beyond endopod and 0.4 beyond more rostrally inserting telson. Statoliths composed of fluorite, diameter 10–11 µm, thickness 7–8 µm (n = 2). Telson length 1.3 times that of ultimate pleomere; width at terminus (measured between lateral margins of latero-terminal spines) is 12% of maximum width and 6% of telson length. Dorsal face of telson subbasally with paramedian fields with 34 and 37 pores, respectively ( Fig. 24F–G View Fig ), pore diameters <3 µm. Telson with triangular scales organized in clusters as in Fig. 14E View Fig . Clusters together form narrow longitudinal ribbon (shaded lateral areas in Fig. 24F View Fig ) proceeding close to each lateral margin between ⅙ and ⅚ of telson length from basis.