Typhlotanais magdalensis, Larsen, Kim & Shimomura, Michitaka, 2007

Larsen, Kim & Shimomura, Michitaka, 2007, Tanaidacea (Crustacea: Peracarida) from Japan. II. Tanaidomorpha from the East China Sea, the West Pacific Ocean and the Nansei Islands, Zootaxa 1464, pp. 1-43 : 20-24

Typhlotanais magdalensis n. sp.

( Figs 8–10 )

Material examined. Holotype, non-ovigerous female, ( KMNH IvR 700.173), Station 12, 31°14.28’N, 131°32.68’E, 367– 254 m, shell sand, East of Cape Toi, Miyazaki, 29 May 2006. Paratypes, 1 non-ovigerous female ( KMNH IvR 700.174) (dissected), same locality; 7 non-ovigerous females ( KMNH IvR 700.175– 700.181), same data; 3 non-ovigerous females ( KMNH IvR 700.182–700.184), Station 2, 31°11.45’N, 131°28.78’E, 223 m, shell sand, east of Cape Toi, Miyazaki, 23 May 2006; 1 non-ovigerous female ( KMNH IvR 700.185), Station KG-2, 17 November 2003, 34°58.192’– 34°58.398’N, 140°05.188’– 140°05.115’E, 186– 169 m, muddy sand, off Boso Peninsula; 1 non-ovigerous female, ( KMNH IvR 700.186), Station 3, 31°18.80’N, 131°28.00’E, 101 m, shell sand, East of Cape Toi, Miyazaki, 20 May 2003.

Diagnosis. Female. Pereonite 1 lateral shield progressing anteriorly beyond posterior margin of cephalothorax. Lateral shield weak on posterior pereonites. Antennule article 3 with apical spiniform process. Chelipeds basis not reaching edge of pereonite 1. Chela shorter than carpus. Pereopod 4–6 unguis serrated but not bifurcate. Uropods longer than pleotelson; endopod and exopod uniarticulated, exopod only half as long as endopod.

Etymology. Named in the honour of the Typhlotanais specialist Dr. Magdalena BłaŻewicz-Paszkowycz.

Description (body of holotype, appendages of dissected paratype).

FEMALE.

Body ( Fig. 8 A). Body length 3.3 mm. Cylindrical, about 9 times as long as broad.

Cephalothorax. Shorter than combined length of pereonites 1 and 2. Eye-lobes absent.

Pereonites. Pereonites 1 and 6 wider than long. Pereonite 2 as wide as long. Pereonite 3–5 longer than wide. Pereonite 1 lateral shield progressing anteriorly beyond posterior margin of cephalothorax, with ventral hyposphera. Succeeding pereonites with lateral shield receding in a posterior direction, to the level of disappearing.

Pleon. Marginally wider than pereon, short (including pleotelson about 15% of total body length). All pleonites subequal, carrying pleopods, weak lateral shield. Pleotelson longer than combined length of two pleonites.

Antennule ( Fig. 9 A). Shorter than cephalothorax. Article 1 longer than rest of antennule, with several simple and setulated setae. Article 2 less than 0.25 times as long as article 1, with three simple distal setae. Article 3 more than twice as long as article 2, with apical spiniform process, two simple setae, one setulated seta and one aesthetasc.

Antenna ( Fig. 9 B). Almost as long as antennule. Article 1 not broader than following articles, naked. Article 2 longer than article 3, with one seta. Article 3 longer than article 1, with one minute dorsal seta. Article 4 longer than other articles, with two simple and four setulated distal setae. Article 5 longer than article 3, with two distal setae. Article 6 minute, with three distal setae.

Mouthparts. Labrum ( Fig. 9 C) flat and with several setules. Mandibles ( Fig. 9 D, E) molar broad and longer than incisor, with terminal ring of denticles, and small proximal spines. Left mandible ( Fig. 9 D) lacinia mobilis and longer than incisor, with four denticles; incisor broad, with two denticles. Right mandible ( Fig. 9 E) incisor divided into two equal parts. Labium ( Fig. 9 F) with inner and outer processes, both with setules. Maxillule ( Fig. 9 G) endite with seven distal spiniform setae, palp shorter than endite, with two terminal setae. Maxilla ( Fig. 9 H) ovoid and featureless. Maxilliped ( Fig. 9 I) basis with one seta at palp insertion. Endites with inner processes and one seta, almost as wide as basis. Palp article 1 naked; article 2 with one outer and three inner setae; article 3 with three inner setae; article 4 with one outer and five inner setae; all inner palp setae setulose. Epignath ( Fig. 9 J) longer than maxillule endite, with inner notches.

Cheliped ( Fig. 10 G). Basis divided unequally by small sclerite attached to the proximal part of basis, shorter than carpus. Merus with one ventral seta. Carpus longer and wider than propodus including fixed finger, with two ventral and two small dorsal setae. Propodus with one seta at dactylus insertion. Fixed finger with two ventral setae and three setae and one small denticle on cutting edge. Dactylus marginally longer than fixed finger.

Pereopod 1 ( Fig. 10 A). Coxa naked. Basis longer than three succeeding articles combined, with several small simple and one setulate setae. Ischium with one seta. Merus as long as carpus, widening distally, with two distal setae. Carpus three-quarters length of propodus, with four distal setae. Propodus shorter than half of basis, with three simple and one robust distal setae. Dactylus and unguis shorter than propodus, not fused into a claw. Dactylus shorter than unguis.

Pereopod 2 ( Fig. 10 B). As pereopod 1 except: merus with few small spines and four distal setae; carpus half as long as propodus, with few small spines and one tubercule; propodus with four distal setae.

Pereopod 3 ( Fig. 10 C). As pereopod 2 except: merus with several small spines and two distal setae.

Pereopod 4 ( Fig. 10 D). Coxa not present. Basis twice as wide as on pereopods 1–3, with two small simple and two setulose setae. Ischium with two setae. Merus with two spiniform serrated distal setae and many small spines. Carpus with one simple dorsodistal seta, clinging apparatus surrounded by small spines. Propodus with two ventrodistal spiniform serrated setae, one dorsoproximal setulated seta, one dorsodistal robust seta and dorsal spine. Dactylus and unguis shorter than propodus and incompletely fused into an elongate claw. Unguis with serrated apex, much shorter than dactylus.

Pereopod 5 ( Fig. 10 E). As pereopod 4 except: carpus with two spiniform serrated setae.

Pereopod 6 ( Fig. 10 F). As pereopod 5 except: propodus with three dorsodistal setae.

Pleopods ( Fig. 10 H). Well developed and held in together in a cone. Basal article naked. Exopod with one outer and many inner plumose setae. Endopod with many inner plumose setae, gap between proximal seta and other setae.

Uropods ( Fig. 10 I). Basal article less than half as long as exopod, naked. Endopod uniarticulated but traces of fusion line can be observed, longer than pleotelson; with two simple and one pinnate medial setae, seven simple and one setulate distal setae. Exopod uniarticulated, only half as long as endopod, with two small medial setae, one short simple and one long thick distal setae.

Remarks. This species belongs to a group of typhlotanaid species which might be raised to genus level in the near future (Dr. M. BłaŻewicz-Paszkowycz, in prep.). This group includes: T. angularis Kudinova-Pasternak, 1966 , T. elegans Kudinova-Pasternak, 1977 *, T. grandis Hansen, 1913 , T. longisetosus Kudinova-Pasternak 1990 , T. parangularis Kudinova-Pasternak, 1975 b, T. rotundirostris Lang, 1970 , and two new species currently under description (Dr. M. BłaŻewicz-Paszkowycz, in prep.). Typhlotanais magdalensis differs from these species by the uniarticulated uropods, and apart from T. parangularis , by the short uropodal exopod. It is differentiated from T. parangularis , by the short uropodal basal article. Because of the currently undergoing revision of the typhlotanaids, no key is given here.

Figures

FIGURE 8. Typhlotanais magdalensis n. sp. A, holotype, female, lateral view. Scale bar = 0.5 mm.

FIGURE 9. Typhlotanais magdalensis n. sp. A, antennule; B, antenna; C, labrum; D, left mandible; E, right mandible; F, labium; G, maxillule; H, maxilla; I, maxilliped; J, epignath. Scale bars = 0.2 mm.

FIGURE 10. Typhlotanais magdalensis n. sp. A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pereopod 6; G, cheliped; H, pleopod; I, uropods. Scale bars = 0.2 mm.