Neotanais krappschickelae, Larsen, Kim & Blazewicz-Paszkwycz, Magdalena, 2003

Larsen, Kim & Blazewicz-Paszkwycz, Magdalena, 2003, A new species of Neotanais Beddard (Crustacea: Tanaidacea) from the Subantartctic, off the Falkland Islands, Zootaxa 339, pp. 1-11 : 3-10

Neotanais krappschickelae n. sp. ( Figs 1–4)

Material examined.– Holotype, non­ovigerous female ( USNM 1017062), Body length 8.8 mm, RV Eltanin Sta. 36/339, 53°05’S, 59°31’W to 53°08’S, 59°24’W, 0 3 December 1962, depth 500–570 meters. Paratype: 1 male, ( USNM 1017063), body length 8.9 mm, same locality.

Additional material: 1 non­ovigerous female (dissected), 2 non­ovigerous females (badly damaged), same locality ( USNM 1017065).

Diagnosis: Female: Body six times longer than broad. Pereonites all wider than long. Pereonite shoulders poorly defined without lateral epimera. Pleonites declining slightly in width in posterior direction, with very small midventral keel. Pleotelson posterior margin straight. Pleotelson lateral margins almost straight, as wide as pleonites, with sparse distal setation. Antennular article 1 short and broad (length/width ratio <3), article 4 shorter than combined length of articles 5–7. Cheliped carpus with several long dorsal setae, dactylus and fixed finger of subequal length, fixed finger bearing two conspicuous denticles on inner margin. Cheliped sclerite, all pereopodal bases, and posterior­lateral edges of pereonites with numerous plumose setae. Uropod as long as pleon. Uropodal exopod with two articles, almost as long as endopod article 1. Uropod attachment anterior to midlength on pleotelson and at 25 angle. Pereopod and uropod attachment in more ventral position than in most other Neotanais .

Male: Cephalothorax in dorsal view more sharply divided into narrow anterior part and broad posterior part, than in female. Antennule longer than that of female, article 4 greatly expanded and densely packed with aesthetascs. Cheliped carpus as long as carapace, with many simple setae on dorsal margin. Propodus (including fixed finger) shorter than carpus. Fixed finger as long as dactylus. Dactylus attached parallel to fixed finger. Cheliped sclerite, pereopod basis, and posterior­lateral edges of pereonites with numerous plumose setae.

Description: Adult non­ovigerous female. Body ( Figs. 1 A, 1B): 5.8 times as long as broad. Body length 8.8 mm.

Cephalothorax: longer than pereonites 1 and 2 combined, longer than broad, with small blunt rostrum, lateral margins smooth.

Pereonites: all rectangular, wider than long, lateral edges straight, posterior­lateral edges with numerous plumose setae. Pereonite 1 longer than half of pereonite 2. Pereonite 5 longest.

Pleon: midventral keel present but small and difficult to observe. Pleonites declining in width in posterior direction, without lateral epimera.

Pleotelson: wider than long (0.4 times), with parallel lateral margins and straight posterior margin, with sparse distal setation. Uropod attachment anterior to midlength on pleotelson and at 25° angle to pleotelson.

Antennule ( Fig. 2 A): marginally shorter than cephalothorax. Article 1 short and broad (length/width ratio <3), with several distally bipinnate distal setae and one short setulated seta. Article 2 half as long as article 1, with several distally bipinnate distal setae. Article 3 length 0.7 times article 2, with two distal setae. Article 4 less than twice as long as combined length of articles 5–7, naked. Article 5 length 0.4 times article 4, with two small setae and multiarticulated aesthetasc. Article 6 shorter than article 5, with two small setae and multiarticulated aesthetasc. Article 7 as long as article 5 with at least three small distal setae.

Antenna ( Fig. 2 B): almost as long as antennule but more slender. Article 1 as long as article 5, twice as wide as succeeding articles, naked. Article 2 longer than article 1, with three distal simple setae. Article 3 length 0.3 times article 2, with one distal seta. Article 4 shorter than article 2, naked. Article 5 slightly shorter than article 4, with two simple and three distally bipinnate distal setae. Article 6 longer than article 3, with four simple distal setae. Article 7 shorter than article 6, with one simple distal seta. Article 8 longer than article 7, with two simple distal setae. Article 9 half as long as article 8, with five simple distal setae.

Mouthparts: labrum not recovered. Mandibular molar as long as incisor, with numerous blunt distal denticles. Left mandible ( Fig. 2 D): incisor blunt, setal row with two finelysetulose blunt spiniform setae, lacinia mobilis well­developed with anterior denticles. Right mandible ( Fig. 2 C): incisor broader than on left mandible, setal row with three spiniform setae of which two are finely­setulose, one is naked and heavy. Labium ( Fig. 2 G): palp elongated with several setules, without thick terminal seta, lobes with distal and medial setulose projection. Maxillule ( Fig. 2 E): outer endite with nine spiniform distal setae as well as several setules on outer margin, inner endite with one long setulose seta and three stout setulose setae as well as several setules on outer margin. Maxilla ( Fig. 2 F): inner lobe of fixed endite with several distally bifurcate setae. Outer lobe of fixed endite with two bifurcated spiniform setae, two simple setae, one distally bipinnate seat, and one medially setose seta. Inner lobe of movable endite with four setae of which one is pinnate. Outer lobe of movable endite with three long simple setae. Maxilliped ( Fig. 3 A): endite almost naked, with one bipinnate seta on distal edge. Basis broad, with one medial bipinnate seta. Conspicuous process for palp attachment with long bipinnate seta, giving the impression of an extra proximal article. Palp article 1 naked and widening distally; article 2 widening distally, with seven bipinnate setae on inner and one simple seta on outer margin; article 3 widest medially with four bipinnate setae and two simple setae on inner margin; article 4 with eight bipinnate distal setae. Epignath ( Fig. 2 H): apex with several fine and long setules.

Cheliped ( Fig. 3 B): sclerite almost circular, with numerous plumose setae. Basis tapering distally, with one small dorso­distal seta. Ischium shaped as a narrow incomplete band extending from under the basis. Merus triangular with one simple seta. Carpus elongate with many long dorsal setae and one ventral seta. Propodus naked other than fixed finger with two conspicuous denticles on inner margin, three setae on inner and two on ventral margin. Dactylus as long as fixed finger.

Pereopod 1 ( Fig. 3 C): coxa small but distinct. Basis with several plumose setae. Ischium with one simple seta. Merus longer than carpus, with several bipinnate distal setae. Carpus with six distal bipinnate setae and one spiniform setae. Propodus longer than carpus, with one dorsal setulose setae midlength, three dorsal bipinnate distal setae, seven on ventral margin, and with one small hook­like three­serrated subdistal seta. Dactylus without spine ring at insertion of unguis, unguis curved.

Pereopod 2 ( Fig. 3 D): similar to pereopod 1 except: ischium with several bipinnate setae. Merus as long as carpus, apparently with simple setae. Carpus with diagonal row of simple setae and ventral simple setae.

Pereopod 3 ( Fig. 4 A): similar to pereopod 2 except; merus shorter than carpus. Carpus with bipinnate setae

Pereopod 4 ( Fig. 4 B): similar to pereopod 3 except: dactylus with spine ring at insertion of unguis.

Pereopod 5 ( Fig. 4 C): similar to pereopod 4.

Pereopod 6 ( Fig. 4 D): similar to pereopod 4 except: propodus with distal row of short curved spiniform setae.

Pleopods ( Fig. 4 E): all five pairs similar. Basal article widening distally, with five plumose setae. Exopod without obvious articulation, with 11 plumose setae outer margin. Endopod with three plumose setae on inner margin and nine on outer margin.

Uropod ( Fig. 4 F): as long as pleon. Basal article twice as long as exopod. Endopod with nine articles of different length, most articles bearing simple or setulose setae, last article with distal setae longer than article itself. Exopod with two articles, almost as long as endopod article 1.

Male: not dissected ( Fig. 1 C) Body length 8.9 mm.

Cephalothorax: in dorsal view more sharply divided into a narrow anterior part and broad posterior part, than in female.

Pereonites: posterior­lateral edges with numerous plumose setae.

Antennule: longer than that of female, article 4 greatly expanded and densely packed with aesthetascs.

Cheliped: sclerite with numerous plumose setae. Carpus as long as carapace, with multiple simple setae on dorsal margin. Propodus (inclusive of fixed finger) shorter than carpus. Fixed finger as long as dactylus. Dactylus attached parallel to fixed finger. Cheliped sclerite less than half as large as basis.

Pereopods: bases with numerous plumose setae.

Etymology: Named in honour of 60th birthday and the scientific achievements of our friend and colleague Dr. Traudl Krapp Schickel,

Remarks: Neotanais krappschickelae n. sp. can be distinguished from all other Neotanais by the combination of characters of: a densely setose dorsal margin of the cheliped carpus, dactylus and fixed finger of subequal length; cheliped sclerite, all pereopodal bases and posterior­lateral edges of pereonites with numerous plumose setae. A further character combination which will separate this species from Gardiner’s ‘micromopher’ group is: pereonite shoulders poorly defined and the pleotelson not fused with pleonites. A character combination which will separate this species from Gardiner’s ‘americanus’ group is: pereonites clearly wider than long, and only two prominent denticles (teeth in Gardiner’s terminology) on the cheliped fixed finger. A character combination which will separate this species from Gardiner’s ‘robustus’ group is: uropodal exopod about as long as first endopod article, and male cheliped fixed finger without large proximal process. The character which will separate this species from Gardiner’s ‘affinis’ group is the cheliped dactylus being as long as fixed finger. Character combinations which will separate this species from Gardiner’s ‘pfaffi’ group are: pereonite shoulders poorly defined, the absence of lateral pleonite epimera, and the fourth antennule article not twice as long as articles 5–7 combined. A character which will separate this species from Gardiner’s ‘hastiger’ group is the cheliped chela not being of the typical ‘fist­shape’ found in the ‘hastiger’ group.

The species most closely resembling N. krappschickelae is N. kurchatovi Kudinova­ Pasternak, 1975 which shares the characters of the pleotelson and cheliped carpus setation but lacks the plumose setation of the cheliped sclerite, pereopodal bases and somites.

The ventral attachment of the pereopods, pleopods, and uropods, along with the heavy plumose setation of the pereopodal bases are also characters seen in Venusticrus and may imply a linkage between the two genera. Neotanais krappschickelae , however, cannot be assigned to Venusticrus since it lacks the characteristic acorn­shaped pelotelson.

The unusual multiarticulated aesthetascs are reported from a number of other Neotanais species: N. giganteus Hansen, 1913 ; N. bacescui Lang, 1968 ; N. pecularis Lang, 1968 ; N. pfaffioides Lang, 1968 , N. armiger Gardiner, 1975 ; N. hastiger Gardiner, 1975 ; N. micromopher Gardiner, 1975 ; N. dinotomer Gardiner, 1975 , N. hamatus Kudinova­Pasternak, 1990 , and N. sp. Larsen & Hansknecht, 2003 but the function of these is unknown.

No other species of Neotanaidae was identified from the Eltanin material and the literature mentions only a few Antarctic or Subantarctic species ( N. affinis Wolff, 1966 ; N. antarcticus Kussakin, 1967 ; N. americanus Beddard, 1886 ; N. magnificus Kudinova­ Pasternak, 1972).

Distribution: Off the Falkland islands, depth 500– 570 m.

Figures

FIGURE 2. Neotanais krappschickelae n. sp. Female. A, antennule; B, antenna; C, right mandible, c 1 blow­up of right molar denticles; D, left mandible, d 1 blow­up of left molar denticles; E, maxillule; F, maxilla: G, labium; H, epignath. Scale bars: 0.1 mm for A, B; 0.01 mm for C – H.

FIGURE 3. Neotanais krappschickelae n. sp. Female. A, maxilliped; B, cheliped; C, pereopod 1; D, pereopod 2. Scale bars: 0.01 mm for A; 0.1 mm for B – D.

FIGURE 4. Neotanais krappschickelae n. sp. Female. A, pereopod 3; B, pereopod 4; C, pereopod 5; D, pereopod 6; E, pleopod; F, uropod. Scale bars: 0.1 mm for A, B; 0.01 mm for C – H.