Metagathotanais loerzae, Guerrero-Kommritz, Jürgen, 2003

Guerrero-Kommritz, Jürgen, 2003, Agathotanaididae (Crustacea: Tanaidacea) from the Angola Basin, Zootaxa 330, pp. 1-15 : 7-11

Metagathotanais loerzae n. sp. ( Figs 3 –4)

Material: 10 specimens, Holotype ZMH K­ 40348, one female, 3.44 mm, RV Meteor 48, DIVA­1, station 340, 5394 m, EBS. Paratypes: ZMH K­ 40349, three females, 2.52, 2.48 and 1.99 mm, RV Meteor 48, DIVA­1, station 340, 5394 m, EBS. ZMH K­ 40350, three females, 3.19, 3.05 and 2.40 mm, RV Meteor 48, DIVA­1, station 344, 5415 m, EBS, ZMH K­ 40351, two females, 3.06 and 2.42 mm, RV Meteor 48, DIVA­1, station 345, 5347 m, BC, ZMH K­ 40352, one female, 3.31 mm, RV Meteor 48, DIVA­1, station 336, 5442 m, BC.

. Metagathotanais loerzae n. sp. Paratype ZMH K­ 40350: a, left cheliped, internal face; b, right cheliped, external face; c, pereopod 1; d, pereopod 2; e, pereopod 3; f, pereopod 4; g, pereopod 5; h, pereopod 6. Scale bar 0.2 mm.

Description: Non­ovigerous female. Body: ( Fig. 3 a, b) 1.99 to 3.44 mm in length, long and slender, about eight times longer than wide, cylindrical. Cephalothorax: ( Fig. 3 c) longer than pleon, shorter than pereonites 1 and 2 together, ventrally with shallow transverse groove posterior of cheliped insertion. Pereon: ( Fig. 3 a, b) pereonite 1 shortest. Pereonites 2, 4 and 5 of equal length. Pereonite 3 longest. Pereonite 6 longer than first and shorter than second. Pleon: ( Fig. 3 a, b) pleonites and pleotelson indistinct, apparently fused.

Antennule: ( Fig. 3 d) composed of four articles. Article 1 longer than rest of antennule, with four long ventral setae and one setule near distal margin. Article 2 with one long and three short distal setae. Article 3 with two terminal setae. Article 4 with five simple terminal setae and one aesthetasc.

Antenna: ( Fig. 3 e) composed of six articles. Article 1 wider than long, naked. Article 2 as long as wide with one small terminal spine. Article 3 as long as wide with one distal spine. Article 4 with one ventral seta, one terminal and two ventral aesthetascs. Article 5 without setae. Article 6 very short with two terminal setae, one as long as rest of antenna.

Labrum: ( Fig. 3 f) hood­shaped, with distal setules.

Mandible: ( Fig. 3 g): well calcified. Lacinia mobilis reduced, pars molaris reduced to only blunt lobes.

Maxillule: ( Fig. 3 h) palp with one long terminal filament. Endite covered with ventral setules. Eight terminal spines.

Maxilla: ( Fig. 3 i) rectangular, naked.

Labium: ( Fig. 3 j) composed of two triangular lobes with one distal tubercle. Naked.

Maxilliped: ( Fig. 3 k) basis heart­shaped, endites naked. Palps composed of four articles. Article 1 naked. Article 2 with two inner strong setae. Article 3 with two inner strong setae. Article 4 with four strong terminal setae.

Epignath: ( Fig. 3 l) ribbon­like without spines or setae.

Cheliped: (Fig. 4a, b) basis wider than long, naked. Merus triangular with one ventral seta. Carpus slender, 2.5 times as long as broad with a smooth ventral tubercle at midlength, with one seta. Propodus twice as long as broad, one ventral seta, three short dorsal setae near cutting edge. One long seta near insertion of dactylus on the inner margin. Cutting edge undulated not forming teeth. Dactylus as long as fixed finger with two short blunt setae at midlength. Unguis not terminal, mounted dorsally on the dactylus.

Pereopod 1: (Fig. 4c) basis six times longer than broad. Ischium short with one ventral seta. Merus with one strong ventral seta. Carpus longer than merus and as long as propodus, with three strong terminal setae. Propodus with two short distal setae. Dactylus about as long as unguis. Unguis slender and pointed.

Pereopod 2: (Fig. 4d) as pereopod 1 except propodus with short terminal spine and only one seta.

Pereopod 3: (Fig. 4e) as pereopod 2.

Pereopod 4: (Fig. 4f) basis 5.5 times as long as broad, with one plumose seta at midlength. Ischium short with one seta. Merus with two strong distal setae. Carpus as long as propodus with three strong distal setae. Propodus with one small terminal spine and two strong straight and one curved setae. Dactylus about as long as unguis. Unguis slender and sharp.

Pereopod 5: (Fig. 4g) as pereopod 4 except ischium without seta, carpus with two strong distal setae.

Pereopod 6: (Fig. 4h) as pereopod 4 except, carpus with one thin dorsal terminal seta, propodus with two curved and one straight strong terminal seta.

Pleopods: absent.

Uropods: ( Fig. 3 m) uropod basis and endopod fused without exopod. Four terminal and one lateral simple setae.

Ovigerous female: unknown.

Male: unknown.

Type locality: Angola Basin, RV Meteor 48, DIVA­1, Station 340, 18°17.3´S 004°41.2´E ­ 18°19.4´S 004°41.9´E, 5394 m.

Etymology: Named for Anne­Nina Lörz, a colleague and friend.

Remarks: This species resembles M. insulcatus . The most distinct differences are in the mouthparts. In M. loerzae , the labrum is hood­like, and in M. insulcatus is rounded. The labium lobes are triangular and naked in M. loerzae , while in M. insulcatus the distal ends are wide and setose. The ischium of pereopods 1 to 3 have one seta and pereopods 4 to 6 have a setulose seta on the basis in M. loerzae . M. insulcatus does not have these setae. The merus of pereopods 1 to 6 of M. loerzae are longer that of M. insulcatus . Metagathotanais is only found at depths greater than 4500 m.

Figures

FIGURE 3. Metagathotanais loerzae n. sp. Holotype ZMH K­ 40348: a, body, dorsal view; b, body, lateral view; c, cephalothorax, ventral view. Paratype ZMH K­ 40350: d, antennule; e, antenna; f, labrum; g, mandibles; h, maxillule; i, maxilla; j, labium; k, maxilliped; l, epignath; m, uropod. Scale bars: a, b, c, 1 mm, all others 0.2 mm.