Paraleptognathia inermis Guerrero-Kommritz 2004, new combination

Paraleptognathia inermis (Hansen, 1913) new combination (Figs 11, 12)

Synonymy: Leptognathia inermis Hansen, 1913

Material examined: 14 individuals. Holotype ZMUC CRU 6821, North Iceland, RV ”Ingolf” St. 126, 67° 19´N 15° 52´W, 293 fm (536 m), one female, two neuters, other material: ZMH K­40536 RV ”Polarstern” St. 39, two females, ZMH K­39759 RV ”Polarstern” St. 179, six females, ZMH K­40532 RV ”Polarstern” St. 31­9, one female, ZMH K­40552 RV ”Polarstern” ARK IX­3 St. 155, two females.

Diagnosis: Cheliped carpal shield very prominent, carpus less then twice as long as wide.

Description: non­ovigerous female. Body (Fig. 11a, b): long, about 6.5 times longer than broad. Body length 2.2 to 3.9 mm. Cephalothorax (Fig. 11a, b): about 1.3 times longer than broad. Pereon (Fig. 11a, b): pereonite 6 shortest, pereonite 1 and 5 of equal length, pereonite 4 longer than 5 and equal to 3; pereonite 2 longest. Pleon (Fig. 11a, b): pleonites equal in length, with one lateral simple seta.

Antennule (Fig. 11c): article 1 longest (longer than the rest articles combined length) with one long simple and four short simple distal setae; article 2 with one long and one short distal setae; article 3 shortest, with three distal simple short setae; article 4 with four terminal setae and one aesthetasc.

Antenna (Fig. 11d): article 1 short semifused to cephalothorax; article 2 as long as broad, with one short spiniform seta; article 3 with one dorsal simple seta; article 4 with a constriction at midlength, two terminal long simple and at constriction one short simple setae; article 5 with one terminal simple seta and one at midlength; article 6 shortest, with four terminal simple setae.

Labrum (Fig. 12d): hood­shaped, with a row of setules on the distal margin.

Mandible (Fig. 12c): well calcified, pars molaris bent ventrally (one broken during dissection), lacinia mobilis broad and pointed.

Maxillula (Fig. 12a): endite with three dorsal and three ventral rows of setules; one thin, one pinnate and six simple terminal spiniform setae.

Maxilla (Fig. 12f): rectangular, smooth.

Labium (Fig. 12e): composed of two triangular lobes with three short distal setae.

Maxilliped (Fig. 12g): endites not fused, as broad as basis, no setae were observed on the basis.

Epignath (Fig. 12a): with no special features.

Cheliped (Fig. 11g): basis as long as carpus; merus with one ventral simple seta; carpus with one ventral and two short simple setae, with tubercle near insertion of chela, carpal shield developed, rounded; propodus about twice as long as dactylus, with four teeth at cutting edge; dactylus smooth.

Pereopod 1 (Fig. 11h): coxa naked; basis three times longer than wide, with a simple short seta; ischium short, with one simple seta; merus as long as carpus, with one spiniform seta; carpus with two spiniform setae; propodus with one terminal spine and a thin dorsal and a short spiniform ventral setae; dactylus smooth; unguis sharp.

Pereopod 2 (Fig. 11i): as pereopod 1, except carpus longer than merus, with three spiniform setae.

Pereopod 3 (Fig. 11j): as pereopod 1, except basis naked.

Pereopod 4 (Fig. 11k): basis about two and a half times longer than broad, with one setulose and one simple ventral seta; ischium short, with one long simple seta; merus with two spiniform setae; carpus longer than merus, with three spiniform setae; propodus longer than carpus, with three spiniform terminal setae; dactylus as long as propodus; unguis sharp.

Pereopod 5 (Fig. 11l): as pereopod 4, except basis with one extra dorsal simple seta; ischium with two simple setae; carpus with four spiniform setae.

Pereopod 6 (Fig. 11m): as pereopod 5, except basis with only one setulose seta; ischium with one simple seta; propodus with four spiniform setae.

Pleopods (Fig. 11e): exopod with nine simple long setae; endopod with ten simple long setae.

Uropods (Fig. 11f): exopod about half as long as first article of endopod. Exopod article 1 with a long simple seta; article 2 with one long simple terminal seta. Endopod article 1 with three distal simple setae; article 2 with five terminal setae.

Type locality: North Iceland, RV ”Ingolf” St. 126, 67° 19´N 15° 52´W, 293 fm (536 m).

Distribution: North Atlantic Ocean, Iceland, Greenland Sea.

Remarks: this species is very similar to P. alba. The carpal shield on the carpus is better developed in P. inermis and the carpus is shorter in P. inermis than in P. alba.

Sieg (1986b) gives in his figures and description some features that were not observed in the present material like the setules on the maxilla, on pereopod 1 and 2, the absence of setules on the labium. Other differences are probably due to the style in which Sieg draw tanaids.