Acanthaspidia matsi Timm, Kaiser & Brandt, 2013, sp. nov.
Creators: name: Timm, Marlene
name: Kaiser, Stefanie
name: Brandt, Angelika
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Acanthaspidiidae
Acanthaspidia
Acanthaspidia matsi

description: Acanthaspidia matsi sp. nov.
(Figs 2–12)
Etymology. The new species is dedicated to the first author’s brother Mats.
Type fixation. Holotype: non-ovigerous female, 12.5 mm long; ZMH K-43191, designated here.
Material examined. Holotype: non-ovigerous female, 12.5 mm long, ANDEEP III, RV Polarstern, EBS, station 133-2, 62°46.73’S – 62°46.33’S, 53°02.57’W – 53°04.14’W, 1584 m, 16.03.2005, ZMH K-43191; Paratypes: 1 adult male, 9.3 mm long, ZMH K-43192; 1 non-ovigerous female (head damaged), ZMH K-43193; 1 nonovigerous female, 12 mm long, ZMH K-43194; 1 adult male (head damaged), ZMH K-43195; 1 adult male, 10.3 mm long, ZMH K-43196; 1 non-ovigerous female, ZMH K-43197; 1 non-ovigerous female, ZMH K-43198; 1 non-ovigerous female, ZMH K-43199, carbon-coated for SEM; 1 non-ovigerous female, ZMH K-43198, carboncoated for SEM; 1 adult male, ZMH K-43199, carbon-coated for SEM; 1 adult male, ZMH K-43200, carbon-coated for SEM; 1 non-ovigerous female, ZMH K-43299, carbon-coated for SEM; 31 specimens (2 adult male, 17 nonovigerous female, 10 juvenile female and 2 manca 2), ZMH K-43201; 31 specimens (2 adult male, 3 non-ovigerous female, 25 juvenile female and 1 manca 3), ZMH K-43202. 1 specimen (non-ovigerous female), ZMH K-43284. All specimens were collected from the same station as holotype.
Type locality. Powell Basin, Weddell Sea, 1584 m.
Distribution. Only known from type locality.
Diagnosis. Cephalothorax width 3.0 times length, with strongly trifid rostrum, each tip length 0.4 times rostrum length. Lateral margins of pereonites 5–7 trifid, pereonites 1, 3, 4 and 6 with 2 strong mid-dorsal spines. Pleotelson spinulated, width 2.3 times length, with 2 strong mid-dorsal spines, lateral margins serrated with 9 spines. Peduncular article 3 of antenna with 2 pointed lateral spines.
Description of holotype and paratype female. Habitus (Figs 2 A – C, F). Body dorsoventrally flattened, scattered with tiny setae on lateral margins of pereonites and pleotelson, widest at pereonites 5 and 6; body length 1.4 times pereonite 5 width. Pereonites 2–4 almost subequal in width, about 1.1 times pereonite 1 width; pereonites 5–7 about subequal in width, width 1.2 times pereonite 1 width. Pereonite 1 length 0.06 times body length; pereonite 1 and 2 subequal in length, pereonite 3 length 1.4 times pereonite 1 length; pereonite 5 length 0.6 times pereonite 1 length; pereonite 6 length 1.4 times pereonite 1 length, pereonite 7 length 0.4 times pereonite 1 length. Pereonites 1, 3, 4 and 6 with 2 strong, dorsal spines, all lateral margins of pereonites pointed, pereonite 1 lateral margin with 1 pointed projection, pereonites 2–5 lateral margin bifid, projections of pereonites 2–4 visibly longer than of pereonite 5; pereonites 6–7 lateral margin trifid. Pleotelson width 2.3 times length. Pleotelson width 0.8 times pereonites 5 width, with 2 mid-dorsal spines. Lateral margins of pleotelson serrated, with 9 spines on both sides.
Cephalothorax (Figs 2 A, C, 12B). Length 3.0 times width, width 0.9 times pereonite 1 width; rostrum pointed, strongly trifid, each tip 0.4 times rostrum length. Rostrum length 0.7 times cephalothorax length; lateral margins bifid, pointed.
Antennula (Fig. 2 E). Length 0.2 times body length, with 21 articles; with 12 aesthetascs, one on almost every article; article 1 circular and broadest, with 9 simple setae laterally and 1 broom seta distally; article 2 length 1.1 times article 1 length, width 0.5 times article 1 width, with 5 simple setae and 1 broom seta laterally, with 3 broom setae medially; article 3 length 0.4 times article 2 length, with 2 simple setae laterally; article 4 short, length 0.3 times article 3 length, with 1 simple seta and 1 broom seta laterally; article 5 length about 1.4 article 4 length, with 1 simple seta laterally; article 6 as long as article 5, with 3 simple setae distally; terminal article with 2 aesthetascs (one broken off) and 1 simple seta distally.
Antenna (Figs 2 A, D, 12D). Length 0.7 times body length, conjoint, consisting of 6 peduncular and 77 flagellar articles. Peduncular articles 1 and 2 broken off, (observed in situ) each with 1 lateral acute spine (see Fig. 12 E). Peduncular article 3 broadest, with 1 distolateral acute spine and 25 simple setae distally and 1 simple seta laterally; peduncular article 4 length 0.3 times article 3 length, with 8 simple setae distally; peduncular article 5 length 3 times article 4 length, with 21 simple setae laterally and 10 simple setae medially; peduncular article 6 longest, length 2.3 times article 5 length, with 29 simple setae laterally; flagellar article 1 longest, conjoint; flagellar articles 1–22 with simple setae irregularly scattered over the surface, following flagellar articles (23–76) with groups of 3–4 simple setae distally; terminal article with 4 simple setae distally.
Mandible (Figs 3 A – C). Incisor process of right mandible with 5 distinct cusps. Spine row with 17 spines, distal ones dentate. Molar process cylindrical, tapering towards distal end. Palpal article 1 with 1 simple seta distally; palpal article 2 1.5 times article 1 length, with 1 simple seta and a row of numerous small setule laterally; palpal article 3 about as long as first, with 7 spine-like setae distally. Incisor process of left mandible with 4 distinct cusps; lacinia mobilis with 4 teeth. Spine row with 12 spines, distal ones dentate. Palpal article 1 with 1 simple seta distally; palpal article 2 1.6 times article 1 length, with 1 simple seta laterally; palpal article 3 about as long as first, with 8 spine-like setae laterally.
Maxillula (Fig. 4 C). Inner endite width 0.3 times outer endite width. Outer endite length 2.2 times width, with 11 robust spine-like setae and 1 seta (broken off). Inner endite with 2 long serrated spine-like setae, 1 small spinelike seta, with numerous simple setae laterally.
Maxilla (Fig. 4 B). Inner endite shortest and broadest, with 6 simple setae and 8 strongly serrated spine-like setae distally; medial and outer endite each with 4 robust setae distally. All three endites laterally surrounded with several simple setae, outer endite with numerous simple setae medially.
Maxilliped (Figs 4 D–G, 12F, H). Left and right maxilliped connected by 8 retinacula. Maxilliped surface curved, scattered with scales. Epipod bluntly pointed, length 3 times width, reaching mid-length of palpal article 2, outer lateral margin strongly convex, inner margin nearly straight. Endite reaching palpal article 4 proximally, with 19 short fan-like setae and numerous simple setae laterally. Palp length 0.7 times maxilliped length; palpal articles 2–5 with several simple setae distomedially and laterally. Palpal article 1 shortest; article 2 broadest, length 0.3 times endite length, width 0.7 times endite width; article 3 length about 0.4 times article 2 length, article 4 length about 1.2 times article 3 length, article 5 subequal article 3 length.
Pereopod 1 (Fig. 5 A). Basis length 3 times width, with 13 simple setae anteriorly and 6 simple setae posteriorly. Ischium length 0.9 times basis length, length 3.1 times width, with 3 simple setae anteriorly, and 5 simple setae posteriorly. Merus length 0.6 times ischium length, length 1.7 times width, with 6 simple setae anteriorly, with 16 simple setae posteriorly. Carpus length 1.6 times merus length, length 3.1 times width; with 8 simple setae anteriorly, with 23 simple setae and 9 unequally bifid setae posteriorly. Propodus length 0.7 times carpus length, length 3.7 times width, with 14 simple setae and 1 broom seta anteriorly, with 15 simple setae and 6 unequally bifid setae posteriorly. Dactylus length 0.3 times propodus length, with 5 simple setae posteriorly and 2 simple setae distally. Unguis length 0.6 times dactylus length, twice as long as ventral unguis.
Pereopod 2 (Fig. 5 B). Basis broken off. Ischium length 3.5 times width, with 2 simple setae and 1 unequally bifid seta anteriorly, with 19 simple setae posteriorly. Merus length about 0.7 ischium length, length 3 times width, with 8 simple setae anteriorly, with 29 simple setae and 1 unequally bifid seta posteriorly. Carpus about as long as ischium, length 4.9 times width, with 13 simple setae and 1 broom seta anteriorly, with 27 simple setae and 6 unequally bifid setae posteriorly. Propodus length about 0.7 times carpus length, length 5.9 times width, with 8 simple setae and 2 broom setae anteriorly, with 21 simple setae and 4 unequally bifid setae posteriorly. Dactylus length about 0.2 times propodus length, with 5 simple setae distally. Unguis of dactylus about 0.9 dactylus length.
Pereopod 3 (Fig. 5 C). Basis 3.3 times longer than wide, with 5 simple setae and 2 broom setae anteriorly, with 8 simple setae posteriorly. Ischium length about 0.9 times basis length, length 3.8 times width, with 3 simple setae and 2 unequally bifid setae anteriorly, with 19 simple setae posteriorly. Merus length about 0.7 times ischium length, length 3.2 times width, with 7 simple setae and 1 unequally bifid seta anteriorly, with 22 simple setae and 1 unequally bifid seta posteriorly. Carpus about as long as ischium, length 5.8 times width, with 8 simple setae anteriorly, with 27 simple setae and 10 unequally bifid setae posteriorly. Propodus length about 0.7 times carpus length, length 6.7 times width, with 19 simple setae anteriorly, with 9 simple setae and 6 unequally bifid setae posteriorly. Dactylus length about 0.2 times propodus length, with 5 simple setae distally. Unguis about 0.9 times dactylus length.
Pereopod 4 (Fig. 5 D). Basis 4.5 times longer than wide, with 6 simple setae and 1 broom seta anteriorly, with 11 simple setae posteriorly. Ischium length about 0.7 times basis length, length 4.1 times width, with 7 simple setae and 1 unequally bifid seta anteriorly, with 11 simple setae posteriorly. Merus length about 0.7 times ischium length, length 3.2 times width, with 5 simple setae anteriorly, with 7 simple setae medially and with 20 simple setae posteriorly. Carpus length about subequal ischium length, length 6 times width, with 10 simple setae and 1 broom seta anteriorly, with 15 simple setae and 16 unequally bifid setae posteriorly. Propodus length about 0.7 times carpus length, length 4.9 times width, with 13 simple setae and 1 broom seta anteriorly, with 7 simple setae and 11 unequally bifid setae posteriorly. Dactylus length about 0.2 times propodus length, with 4 simple setae distally. Unguis about 0.9 times dactylus length.
Pereopod 5 (Fig. 6 A). Basis length 4.3 times width, with 7 simple setae and 1 broom seta anteriorly, with 2 simple setae posteriorly. Ischium length about 0.8 times basis length, length 3.6 times width, with 4 simple setae and 1 unequally bifid seta anteriorly, with 16 simple setae posteriorly. Merus length 0.7 times ischium length, length 3.7 times width, with 9 simple setae anteriorly, with 16 simple setae and 4 unequally bifid setae posteriorly. Carpus length about 1.4 times merus length, length 5.9 times width, with 10 simple setae and 1 broom seta anteriorly, with 6 simple setae and 26 unequally bifid setae posteriorly. Propodus length 0.8 times carpus length, length 7.9 times width, with 15 simple setae and 1 broom seta anteriorly, with 12 simple setae and 8 unequally bifid setae posteriorly. Dactylus length 0.2 times propodus length, with 6 simple setae distally. Unguis about 0.9 times dactylus length.
Pereopod 6 (Fig. 6 B). Basis length 4.2 times width, with 8 simple setae anteriorly, with 6 simple setae and 3 broom setae posteriorly. Ischium length about 0.8 times basis length, length 3.9 times width, with 11 simple setae anteriorly, with 2 simple setae posteriorly. Merus length 0.7 times ischium length, length 4.1 times width, with 5 simple setae anteriorly, with 6 simple setae medially, with 20 simple setae and 1 unequally bifid seta posteriorly. Carpus length about 1.4 times merus length, 5.7 times longer than wide, with 16 simple setae and 1 broom seta anteriorly, with 16 simple setae and 16 unequally bifid setae, posteriorly, with 1 simple seta and 3 unequally bifid setae distally. Propodus length 0.8 times carpus length, length 8.4 times width, with 10 simple setae and 1 broom seta anteriorly, with 11 simple setae and 9 unequally bifid setae posteriorly. Dactylus length 0.2 propodus length, with 7 simple setae distally. Unguis about 0.9 times dactylus length.
Pereopod 7 (Fig. 6 C). Only basis present, basis length 5.3 times width, with 5 simple setae anteriorly and 10 simple setae posteriorly.
Operculum (female pleopod 2, Figs 2 F, 4A, 12G). Length 1.2 times width. Dorsal surface with several simple setae, lateral margin with numerous (> 70) simple setae.
Uropods broken off in all specimens.
Description of paratype male. Habitus (Figs 7 A–F, 12A, C, E). Adult male 9.3 mm long, length 1.5 times pereonite 5 width. Pereonites 5–7 about subequal in width, width 1.4 times pereonite 1 width, pereonites 5–6 about subequal in length, length 1.3 times pereonite 1 length. Pereonite 7 length 0.4 times pereonite 1 length. Pleotelson width 1.8 times length, width 0.9 times pereonite 5 width.
Cephalothorax (Figs 7 A, D 12C). Length 3 times width, width 0.9 times pereonite 1 width; rostrum trifid, length 0.5 times cephalothorax length; lateral margins bifid, pointed.
Antennula (Fig. 8 B). Length same as in female, with 18 articles; with 15 aesthetascs, with one on almost every article (except articles 1–6); article 1 broadest, with 1 simple seta medially, with 3 simple setae laterally, with 3 simple setae and 1 broom seta distally; article 2 length 0.9 times article 1 length, width 0.5 times article 1 length, with 9 simple setae and 2 broom setae laterally, with 1 simple seta medially and 3 simple setae and 1 broom seta distally; article 3 length 0.5 times article 2 length, with 2 simple setae laterally; article 4 short, length 0.4 times article 3 length, with 1 simple seta and 2 broom setae laterally; article 5 length about 1.4 times article 4 length, with 1 simple seta distally; article 6 as long as article 4, with 2 simple setae distally; terminal article with 1 aesthetasc and 1 simple seta distally.
Antenna (Figs 8 C, 12D). Length same as in female, consisting of 6 peduncular and 58 flagellar articles. First and second peduncular article with lateral acute spine; peduncular article 3 broadest, with distolateral acute exopod and distomedial acute projection, with 9 simple setae distally and 7 simple setae laterally; peduncular article 4 length 0.1 times article 2 length, with 6 simple setae laterally; peduncular article 5 length 10 times article 4 length, with 19 simple setae laterally and 6 simple setae medially; peduncular article 6 longest, length 1.9 times article 5 length, with 42 simple setae laterally, 11 simple setae medially and 1 broom seta laterally; flagellar article 1 conjoint. Flagellar articles with irregularly scattered groups of 3–4 simple setae distally or laterally; terminal article tip broken off.
Mandibles (Figs 8 D–F). Incisor process of right mandible with 5 distinct cusps. Spine row with 15 spines, distal ones dentate; palp length subequal mandibular body length; palpal article 2 length 2.3 times article 1 length; palpal article 3 length 0.7 times article 2 length, with 5 spine-like setae distally. Incisor process of left mandible with 5 distinct cusps; lacinia mobilis with 4 teeth. Spine row with 13 spines, distal ones dentate; palp length 0.9 times mandibular body length; palpal article 2 length 3.3 times palpal article 1 length; palpal article 3 length 0.7 times article 2 length, with 6 spine-like setae.
Hypopharynx (Fig. 8 A). Consisting of two lobes.
Maxillula (Fig. 9 B). Inner endite width 0.2 times outer endite width. Outer endite length 2.2 times width, with 12 robust spine-like setae (some of these serrated). Inner endite with 1 serrated spine-like seta and 1 robust seta (broken off). Both endites surrounded by numerous simple setae laterally, outer endite with several simple setae medially.
Maxilla (Fig. 9 C). Innermost endite with 6 distal robust serrated spine-like setae and 4 simple setae distally; medial endite with 4 robust setae distally, outer endite with 3 robust setae and 3 serrated spine-like setae distally; outer and inner endite surrounded by numerous simple setae.
Maxilliped (Figs 9 A, 12F, H). Similar to female, except palp article 5 length 0.6 times article 4 length.
Pereopod 1 (Fig. 10 A). Only the basis present, basis 4.9 times longer than wide with 7 simple setae anteriorly and 1 simple seta posteriorly.
Pereopod 2 (Fig. 10 B). Length-ratio of joints similar to female paratype (only indicated when different to female). Basis length 4.7 times width, with 2 simple setae and 3 broom setae anteriorly. Ischium 0.6 times basis length, length 3.2 times width, with 4 simple setae anteriorly, with 8 simple setae posteriorly. Merus length 3 times width, with 2 simple setae anteriorly, with 25 simple setae posteriorly. Carpus length 5.1 times width, with 1 simple seta and 1 broom seta anteriorly, with 21 simple setae and 4 unequally bifid setae posteriorly, with 5 unequally bifid setae distally. Propodus length 5.5 times width, with 12 simple setae, 1 unequally bifid seta and 1 broom seta anteriorly, with 16 simple setae and 4 unequally bifid setae posteriorly. Dactylus with 5 simple setae distally. Ungius similar to female paratype.
Pereopod 3 (Fig. 10 C). Length-ratio similar to female paratype. Basis length 4.8 times width, with 3 simple setae and 4 broom setae anteriorly and 4 simple setae posteriorly. Ischium length 3.4 times width, with 5 simple setae and 1 unequally bifid seta anteriorly and 9 simple setae posteriorly. Merus length 2.9 times width, with 2 simple setae anteriorly, with 15 simple setae and 2 unequally bifid setae posteriorly. Carpus length 7.7 times width, with 2 simple setae and 2 broom setae anteriorly, with 14 simple setae and 8 unequally bifid setae posteriorly, with 2 robust setae and 1 unequally bifid seta distally. Propodus length 6.5 times width, with 10 simple setae and 1 broom seta anteriorly, with 11 simple setae and 9 unequally bifid setae posteriorly. Dactylus with 4 simple setae laterally and 6 simple setae distally. Ungius similar to female paratype
Pereopod 4 (Fig. 10 D). Length-ratio similar to female paratype. Basis length 3.7 times width, with 2 broom setae anteriorly and 4 simple setae posteriorly. Ischium length 3.8 times width, with 4 simple setae anteriorly, with 6 simple setae posteriorly. Merus length 3.2 times width, with 3 simple setae and 1 unequally bifid seta anteriorly, with 10 simple setae and 1 unequally bifid seta posteriorly. Carpus length 5.8 times width, with 11 simple setae and 1 broom seta anteriorly, with 14 simple setae, 5 unequally bifid setae and 4 setae (broken off) posteriorly, with 2 robust setae and 1 unequally bifid seta distally. Propodus length 6.7 times width, with 19 simple setae anteriorly, with 15 simple setae and 7 unequally bifid setae posteriorly. Dactylus with 7 simple setae distally. Ungius similar to female paratype
Pereopod 5 (Fig. 10 E). Length-ratio similar to female paratype. Basis length 3.7 times width, with 1 simple seta and 1 broom seta anteriorly, with 5 simple setae posteriorly. Ischium length 1.4 times width, with 4 simple setae anteriorly, with 9 simple setae posteriorly. Merus length 3.2 times width, with 2 simple setae anteriorly, with 9 robust simple setae posteriorly, with 3 simple setae distally. Carpus length 1.5 times merus length, length 4.9 times width, with 4 simple setae and 1 broom seta anteriorly, with 9 simple setae and 8 unequally bifid setae posteriorly, with 4 unequally bifid setae laterally, with 2 robust setae and 1 unequally bifid seta distally. Propodus length 6.2 times width, with 3 simple setae and 1 broom seta anteriorly, with 13 simple setae and 8 unequally bifid setae posteriorly, with 1 simple seta laterally. Dactylus with 6 simple setae distally. Ungius similar to female paratype.
Pereopod 6 (Fig. 10 F). Length-ratio similar to female paratype. Basis length 5.2 times width, with 1 simple seta and 2 broom setae anteriorly, with 5 simple setae posteriorly. Ischium length 4.1 times width, with 4 simple setae anteriorly and 4 simple setae posteriorly. Merus length 4.4 times width, with 5 simple setae anteriorly, with 7 simple setae and 1 unequally bifid seta posteriorly. Carpus length 6.3 times width, length 1.5 times merus length, with 4 simple setae and 1 broom seta anteriorly, with 1 simple seta and 15 unequally bifid setae posteriorly, with 3 unequally bifid setae distally. Propodus length 7.3 times width, with 10 simple setae anteriorly, with 7 simple setae and 10 unequally bifid setae posteriorly. Dactylus with 6 simple setae distally. Ungius similar to female paratype.
Pereopod 7 (Fig. 10 G). Only basis and ischium present; length-ratio similar to female paratype. Basis length 5.1 times width, with 3 simple setae and 3 broom setae anteriorly, with 7 simple setae posteriorly. Ischium length 4.6 times width, with 4 simple setae and 1 unequally bifid seta anteriorly, with 6 simple setae posteriorly.
Pleopod 1 (Figs 11 A–B). Smooth, tapering towards distal end. Length 2.5 times proximal width, distal width 0.4 times proximal width. Tips bilobed, slightly pointed in ventral view, with numerous (> 50) simple setae distally. Medial and lateral lobes about subequal in width, lateral lobes length 1.3 times medial lobes length.
Pleopod 2 (Fig. 11 C). Sympod length 2.9 times width. Lateral margin slightly rounded with 16 simple setae; distal margin with 5 slightly plumose setae, 12 minute setae, and 6 simple setae. Endopod inserting about 0.5 from distal tip of sympod. Stylet long and slender, length 1.6 times sympod length. Exopod small, bilobed with several fine setae.
Pleopod 3 (Fig. 11 D). Length 2.5 times width; sympod short and coalescing with endopod. Medial and lateral margins with fine setules. Endopod with 2 plumose setae distally and 5 medially; exopod length 0.9 times endopod length, consisting of 2 articles, distal article with 20 plumose setae distolaterally.
Pleopod 4 (Fig. 11 E). Sympod short, quadrangular; exopod more slender than endopod, both curved.
Pleopod 5 (Fig. 11 F). Only one small oval lobe.
Remarks. Acanthaspidia matsi sp. nov. can be distinguished from all other species in the genus by the strongly trifid rostrum (each tip length 0.4 times rostrum length), by possessing 2 mid-dorsal spines on pereonites 1, 3–4 and 6 and by a spinulated pleotelson bearing 2 robust mid-dorsal spines. The new species most closely resembles A. typhlops. The latter can be distinguished from A. matsi sp. nov. by the following characters: first article of antennula quadrangular (versus circular in A. matsi sp. nov.), second article without broom setae (versus 3); third peduncular article of antenna with 1 short smooth, blunt spine (versus 2 long, pointed lateral spines); lateral margins of pleotelson with 6 strong spines (versus 9). Acanthaspidia matsi sp. nov. is also similar to A. natalensis, which differs from the new species by the following characters: lateral margins of pereonites 5–7 with 1 rounded projection; lateral margins of pleotelson with 6 strong spines (versus 9). Acanthaspidia bifurcatoides Vasina & Kussakin, 1982 also resembles A. matsi sp. nov., but can be distinguished from the new species as follows: lateral margins of pleotelson with 7 strong spines (versus 9).
description: Published as part of Timm, Marlene, Kaiser, Stefanie & Brandt, Angelika, 2013, A new species of Acanthaspidia Stebbing, 1898 (Isopoda, Asellota, Acanthaspidiidae) from the bathyal Weddell Sea (Southern Ocean), pp. 238-258 in Zootaxa 3692 (1) on pages 242-256, DOI: 10.11646/zootaxa.3692.1.12, http://zenodo.org/record/222333