Paraleptognathia alba Guerrero-Kommritz 2004, new combination

Paraleptognathia alba (Hansen, 1913) new combination (Figs 1, 2)

Synonymy: Leptognathia alba Hansen, 1913

Material examined: two individuals. Holotype ZMUC CRU 5247 non ovigerous female, 3.7 mm, south west of Cape Farewell, RV ”Ingolf” St. 22, 58° 10´N 48° 25´W, 1845 fm (3376 m). Other material ZMUC CRU 3944 non ovigerous female, 2.6 mm, East Iceland, Bakkefjord (Bakkafloi), RV ”Diana” St 8., 24– 30 m.

Diagnosis: Chela smooth, carpal shield developed and rounded, carpus twice as long as wide.

Description: non­ovigerous female. Body (Fig. 1a, b): long, about seven and a half times as long as wide. Pleon shorter than cephalothorax. Body length 2.6 to 3.7 mm.

Cephalothorax (Fig.1a, b): one and a half times longer than wide. Pereon (Fig.1a, b): pereonite 6 shortest, pereonite 1 as long as 5, pereonites 2, 3 and 4 of equal length. Pleon (Fig.1a, b): pleonites of equal length; pleotelson rounded, apex with a tubercle.

Antennule (Fig. 2b): article 1 longer than all the others together, with one distal simple seta; article 2, one third of length of first, with two distal simple setae; article 3 shortest with one distal simple seta; article 4 with four terminal setae.

Antenna (Fig. 2c): article 1 short, semifused to the cephalothorax; article 2 as long as wide; article 3 half as long as second; article 4 longest with two distal setae; article 5 with one terminal seta; article 6 shortest with three terminal setae.

Cheliped (Fig. 2a): basis as long as chela; merus triangular with one ventral simple seta; carpus longer than wide with one ventral seta at midlength, carpal shield developed and rounded; propodus smooth, twice as long as dactylus, cutting edge with four teeth; dactylus smooth, naked.

Pereopod 1 (Fig. 2e): coxa naked; basis three times longer than wide, naked; ischium short with one simple, thin seta; merus smooth with one spiniform seta; carpus smooth with two spiniform setae; propodus smooth with one distal short spiniform seta and a dorsal spine; dactylus smooth, unguis half as long as dactylus, sharp.

Pereopod 2 (Fig. 2f): as pereopod 1, except carpus with three spiniform setae; propodus with one simple thin seta dorsally, near spine.

Pereopod 3 (Fig. 2g): as pereopod 2, except basis four times longer than wide.

Pereopod 4 (Fig. 2h): basis about three times as long as wide, naked; ishium short, naked; merus smooth, with two spiniform setae; carpus smooth with three spiniform setae; propodus smooth with four terminal spiniform setae; ungius sharp, about half length of dactylus.

Pereopod 5 (Fig. 2i): as pereopod 4, except ischium with simple seta; propodus with three spiniform setae.

Pereopod 6 (Fig. 2j): as pereopod 4, except ischium with seta.

Pleopods: present, not illustrated.

Uropods (Fig. 2d): basal article rectangular, naked; exopod half as long as article 1 of endopod. Exopod article 1 with one simple terminal seta; article 2 with one terminal long seta. Endopod article 1 shorter than article 2, with one setulose and one simple seta distally; article 2 with four long distal setae.

Type locality: south west of Cape Farewell RS ”Ingolf” St. 22, 58° 10´N 48° 25´W, 1845 fm (3376 m).

Distribution: this species is only known from Iceland and south Greenland.

Remarks: because this species is represented by two individuals, the holotype and one animal misidentified as Leptognathia sarsii Hansen, 1909, dissection was not possible and mouthparts were not investigated. The antenna and the pleopods could not be studied properly. This species can clearly be distinguished from other Paraleptognathia species in the shape of the cheliped carpus which is twice as long as wide. The ventral flat tubercles mentioned by Hansen (1913) on the pleon are not characteristic for this species, they can be observed on other Paraleptognathia.