Antatelson antennatum Bellan­Santini & Ledoyer, 1974

Krapp-Schickel, Traudl, 2006, Thaumatelsonine Stenothoids (Crustacea, Amphipoda). Part 2, Zootaxa 1165, pp. 1-31 : 17-25

Antatelson antennatum Bellan­Santini & Ledoyer

Antatelson antennatum Bellan­Santini & Ledoyer 1974 , 701 fig. 39

Material examined UL/OC­458 King George Island, Admiralty Bay, 46 m, 17.3.1985, 3 ind., 3 mm.

Diagnosis

Antenna 1 article 1 nasiform process reaching half of article 3. Gnathopods 1, 2 both palmar corner rounded, hind margins parallel to front margins; gnathopod 1, 2 propodi twice as long as large. Pereonite 4 widened, without any process. Uropods slightly surpassing length of telson.

Remarks

Probolisca nasutigenes and Antatelson antennatum are strikingly similar and both described from Kerguelen, thus I argued that some details may have been overlooked or not observed sufficiently, e.g. the telson of Probolisca nasutigenes is described as ordinary, not "twisted", but Stebbing mentioned "upturned margins" ( Stebbing 1906, 183, not in the original description).­ But A. antennatum (2mm length) is described as living among red algae ( Bellan­Santini & Ledoyer 1974, 641, see K­80, K­81, K­83, 50 m depth), the here studied material from King George Island (3 mm) comes from medium to coarse sand and shell, while Stebbing’s Metopa nasutigenes (4.5 mm) is found in 222 m depth among volcanic mud (also Bellan­Santini & Ledoyer 1974 found the latter species with 1 specimen at 50 m depth in the Kerguelen). ­ Thus the synonymy of these two "nosebearing", extremely similar species could not be attested.

In the material from King George Island uropod 1 is longer than drawn in Bellan­ Santini, 1974 and thus matching with Stebbing, 1888, also uropod 3 article 2 seems longer, but the articulation is not very clear (the same also in Ausatelson ).

Distribution Antarctica, Kerguelen, King George Island.

Ecology Red algae, medium to coarse sand and shell, mud. About 50 m depth.

Verticotelson gen. nov.

Type species. Verticotelson mantis n. sp. Monotypic.

Characters

Antenna 1 peduncle article 1 longer than first body segment, with long nasiform process; accessory flagellum absent. Mandible palp lacking. Maxilla 1 palp with 2 articles. Maxilla 2 plates in tandem position, subequal. Maxilliped outer plates lacking, palp slender and narrow. Coxa 4 trapezium­shaped. Gnathopod 1 propodus long and narrow, subrectangular, subchelate; gnathopod 2 with propodus, carpus and merus extremely long and narrow, dactylus minute. Urosome segments fused. Telson thickened, fleshy, lateral area larger than dorso­ventral one, thus kept in vertical position.

Etymology For stressing the rudder­like telson with large lateral area.

Verticotelson mantis n.sp.

Fig. 7–10

Material examined

Holotype. Australia, Victoria, Western Port (38 o 26.48’S, 145 o 13.03’E), 23 m, Sand , Smith­McIntyre grab, Coleman, N, 25 November 1973 (stn WBES 1748 ), NMV J39602 (1 male, 2.5 mm).

Allotype. Same locality as holotype, NMV J52748 (1 female, 2.5 mm).

Paratypes. Same locality as holotype NMV J39600 (1 ind. 2.5 mm); (38 o 24.36’S, 145 o 14.66’E) , 20 m, Sand, Smith­McIntyre grab, Coleman coll, N, 21 November 1973 (stn WBES 1729 ), NMV J39601 (2).

Other material. Australia, Victoria, Western Port (38 o 29.78’S, 145 o 6.28’E), 24 m, Sand, Smith­McIntyre grab, Coleman, N, 25 November 1973 (stn WBES 1746), NMV J39603 (juvenile 1.2 mm); Off Crib Point (38 o 22.06’S, 145 o 14.10’E), 13 m, reef songe, Smith­McIntyre grab, Gilmour, AJ , Marine Studies Group, Melita, FV, 5 March 1965 (stn CPBS­S 33 ), NMV J39604 (1 juvenile) .

Diagnosis

Antenna 1 peduncle article 1 huge, nasiform process as long as article, rest of antenna continuing in a right angle. Eyes rounded. Gnathopod 2 characteristically lengthened with very long carpus and reduced dactylus. Pereopods feeble, scarcely beset with setae. Uropods slim and naked. Telson elevated.

Description

Length, 1.5–2.5mm

Antenna 1 <antenna 2; article 1 with nasiform process, longer than first body segment, front end somewhat serrated and beset with single setae. Insertion of article 2 medioventrally on article 1, creating a right angle. Accessory flagellum lacking. Article 3 subequal article 2, flagellum with 3 segments. Antenna 2 article 5> article 4, flagellum with 8 articles.

Mandibular incisor with sharp teeth, lacinia mobilis like a scraper with many short teeth; all other parts smooth and reduced, palp lacking. Maxilla 1 inner plate lacking seta, round, outer plate with 6 robust setae and some subapical setae. Maxilla 2 inner plate somewhat shorter and broader than outer, both rounded and in tandem position, short setae distally. Maxilliped inner plates small, separated, outer plates lacking, palp narrow, with 4 articles, the second one on outer margin densely beset with setae.

Coxa 1 subquadrate, minute. Coxa 2, 3 rectangular, length more than twice of width; coxa 4 trapezoidal to rectangular, width> length. Coxa 5–7 subequal, minute, even shorter than coxa 1.

Gnathopod 1 basis ratio length to width = 5; ischium with few long setae on outer margin, merus and carpus with many fine setae on outer margin; carpus triangular, length subequal to propodus; propodus rectangular, length> 3 times width, on outer margin 3 combed robust setae, hind margin finely serrated; dactylus curved, palm margin well defined by corner and robust seta. Gnathopod 2 strongly aberrant having a strong long basis with length 4.5 times the width, and propodus + carpus extremely thin, carpus length: width = 12, propodus length: width = 7. The dactylus is reduced, distal part of propodus with a transversally "striped" area which seems to have a special, but hitherto unknown function.

Pereopods like in most of thaumatelsonids feeble and with only few setae.

Urosomites fused. Uropods extending less far posteriorly in succession, even in uropod 1 lower ramus> the upper one, which is longer than uropod 2 lower ramus> upper one> uropod 3> tip of telson.

Telson insertion hidden under end of urosomite 1; there was no fusion with urosomite 3 visible; distally rounded, very short medial setae.

Etymology

Mantis, ­eos is the Greek expression for prophet, soothsayer; the situation of the folded long gnathopod 2 reminds of praying arms like in Mantis religiosa. Used as noun in apposition.

Distribution Australia, Victoria, off Melbourne (Phillip Island, Western Port).

Ecology Fine sand, sponges, 13–24m depth. FIGURE gnathopod 2; d) Gn2 distally enlarged; Gn1, Gn 2 in scale x of Fig. 2 = 0.2mm; Gn1 enlarged in scale x = 0.1mm; Gn2 enlarged in scale x = 0.04 mm; e) peraeopod 3; f) peraeopod 4; g) peraeopod 5; h) peraeopod 6; i) peraeopod 7; P3,4 in scale x = 0.4 mm; P5,6,7 in scale y of Fig. 2 = 0.1mm; k) pleon; l) urosomite 1; m) telson; n) uropod 1; o) uropod 2; p) uropod 3; k,l,m in scale y = 0.1mm; below l­p in scale y = 0.4mm.

Prothaumatelson Schellenberg, 1931

Schellenberg, 1931, p. 113

Type species. Prothaumatelson nasutum Chevreux.

Characters

Antenna 1 article 1 nasiform; accessory flagellum absent. Mandible palp with 1 long article; maxilla 1 palp with 2 articles; maxilla 2 ordinary. Gnathopod 1 and 2 very different in size and shape, gnathopod 1 small, subchelate­rectipalmate, merus incipiently chelate; gnathopod 2 enlarged, propodochelate. Pereopod 3–7 basis rectilinear. Pereonite 4 elongate, tumid. Pleonite 3 lacking process. Urosomite 1 folds weakly vaulting over urosomite 2. Urosomites 2+3 coalesced. Telson huge, vertically elevated, laterally compress, lateral surface area equal to lateral area of urosome.

Prothaumatelson nasutum ( Chevreux, 1912)

Chevreux, 1912, 5, 212 ( Thaumatelson nasutum ). Chilton, 1912, 201, 483, t. i, fig. 16, 17 ( Thaumatelson inermis ). Chevreux, 1912, 109– 113, fig. 16–18 ( Thaumatelson nasutum ). Schellenberg, 1931, 113 ( Prothaumatelson nasutum ). Barnard, K.H. 1932, 112–113. Thurston, 1974, 25–26.

Diagnosis

A1 article 1 strongly nasiform; Md palp well developed, no articulation visible; gna­ thopod 1 subchelate­rectipalmate, gnathopod 2 propodochelate, dactylus ca 40% propo­ dus. Urosomite 1 has a short, but clearly visible fold over the following segment folding dorsally, reaching, but not overlapping insertion of telson. Uropod 3 shorter than telson, scarcely surpassing peduncle of uropod 2. Telson vertically inserted and huge, lance­ or blade­shaped, with a sclerotified dorsal crest.

Material examined

Type material SIW, 1 slide, 1 ind. in alcohol, Inv. Nr. 195166, 4 ind. in alcohol, Inv. Nr. 195167.

Other material. SIW, 1 ind. alcohol, Inv. Nr. 149531. MNHUB Grytviken, S­ Georgia, Nr. 22805 18 ind. in alcohol (leg. + det. Schellenberg). ­ BML, many ind. in alcohol, Inv. Nr. 1969.143–147 Signy Isl., S­Orkneys (leg. + det. Thurston), 143, 1 ind., 144, 1 female (2 eggs) 2mm; 145, 1 ind. 2.2mm; 146, 2 ind. 1.2 mm; 147 1 fem. (1 egg) 2mm. UL/OC­ 590 King George Isl., Admiralty Bay, 25.1.1988 2 ind. leg. Jazdzewski. UL /28 King George Isl. , Admiralty Bay, from rhizoids of Phyllogigas grandifolius 30–60m, 24.1. 1980 .

Distribution Subantarctic and near islands.

Ecology In large algae, probably in the epizoic growth on the holdfasts, 5–15 m ( Thurston 1974, 25); 1– 60m.

Ausatelson J.L. Barnard, 1972

Ausatelson J.L. Barnard (1972a, 312)

Type species. Ausatelson ule L.J. Barnard, 1972a .

Characters

Antenna 1 nasiform process on article 1. Accessory flagellum minute to absent. Palp of mandible 1­articulate; palp of first maxilla 2­articulate. Inner plate of maxilla 2 obsolescent. Inner plates of maxillipeds partially fused. Gnathopod 1 small, almost simple, palm oblique and longer than posterior margin of propodus; merus not lengthened. Gnathopod 2 enlarged, palm weakly oblique, merus short, lobed. Pereonite 4 highly elongate and tumid. Pleonites 5–6 coalesced; pleonite 3 dorsally tumid but lacking process; pleonite 4 weakly extended posterodorsally. Telson huge, laterally compressed, lateral surface area equal to lateral area of urosome.

Remarks

This genus has closest relationship to Antatelson (see humps on pleonite 3), but gnathopods are here much more different in size and shape from each other, mandible palp has one article (vs. 2?– 3 in Antatelson ) and pereonite 4 is tumid (vs. smooth in Antatelson ).

Figures

FIGURE 2. Thaumatelson herdmani Walker. a) A1 laterally and dorsally; b) A2, c) mandible; d) maxilla 1; e) maxilla 2; f) gnathopod 1; g) gnathopod 2; gnathopods in scale x = 0.1mm; mouthparts in scale y = 0.1mm.

FIGURE 7. Verticotelson mantis n.sp. a) habitus female ad. 2.5mm; b) habitus iuv. 2.0 mm in scale x of Fig. 2= 1mm; c) head in scale x= 0.2mm; d) lower lip; e) mandible; f) maxilla 1; g) maxilla 2; h) maxilliped; Md, Mx1, Mxp and LL in scale x = 0.1 mm; Mx2 in scale x = 0.05mm.

FIGURE 9. Verticotelson mantis n.sp.: a) antenna 1; b) habitus male. Sketches without scale.

FIGURE 10. SEM of Verticotelson mantis n.sp.: a) head with antenna 1; b) gnathopod 1 propodus tip with minute dactylus; c) coxa 2 and gnathopod 2; d) head with antenna 1, 2, gnathopod 1; e), f), g) urosomites and telson.