Forcipatia rotundicauda ( Kudinova-Pasternak, 1970 )

Bird, Graham J., 2007, Leptognathiidae Sieg, 1976 *, Zootaxa 1599, pp. 61-85 : 77-79

Forcipatia rotundicauda ( Kudinova-Pasternak, 1970)

Figures 7–8

Leptognathia rotundicauda Kudinova-Pasternak, 1970: 363 –364, fig. 15. Larsen, 2005; 200 (remarks and comparison with L. longimanus Larsen ).

Material examined. 1 preparatory male (?) and 1 juvenile ( KMNH IvR 500.179), station TD-4, 39°27.08’N 143°37.79’W, 3146–3272 metres, 28 September 2001.

Description (supplementary to Kudinova-Pasternak 1970).

Preparatory male (?). Body ( Fig. 7 A). Stout, five times as long as broad, length 1.4 mm.

Cephalothorax. As long as broad, with round lateral margins, weak rostrum and seta near base of each antennule.

Pereonites. All shorter than broad, with lateral process over pereopod insertion, 0.31, 0.56, 0.53, 0.59, 0.58 and 0.33 times as long as broad respectively.

Pleon ( Fig. 7 B). 23% of body length. Pleonite 5 with lateral seta, sternites with only low ventral profile.

Pleotelson. As long as two preceding pleonites, conical, with small deflexed apex and large anal valves.

Antennule ( Fig. 7 C). Longer than carapace. Article 1 just less than half of total length, stout, 2.4 times as long as broad, with disto-lateral seta and three more proximal sensory setae. Article 2 very stout, just longer than broad, with lateral and medial setae. Article 3 short, as long as broad, with two unequal setae. Article 4 as long as article 2, almost three times as long as broad, with several terminal setae and an aesthetasc.

Cheliped ( Fig. 7 D). Basis attached via a sclerite to carapace. Merus with long seta. Carpus about twice as long as broad, with ventral seta and small disto-dorsal seta, without shield; propodus 1.5 times as long as carpus and 0.4 times as deep as long, with two long ventral setae, two unequal medial setae and lateral seta near articulation with dactylus. Fixed finger with curved terminal spine, two or three small teeth on incisive margin and three unequal lateral setae. Dactylus long and strongly deflexed distally, with proximo-medial seta.

Pereopod 1 ( Fig. 8 A). Larger than pereopods 2–3. Coxa annular, with seta. Basis slender, about 5–6 times as long as broad. Ischium with seta half as long as merus. Merus twice as long as broad, with ventral seta. Carpus rectangular, 2.25 times as long as broad, with two unequal dorsal setae. Propodus longer than carpus and four times as long as broad, with three distal spiniform setae. Dactylus and unguis together shorter than propodus, unguis tip spatulate.

Pereopod 2 ( Fig. 8 B). About 85% length of pereopod 1, similar but with sensory seta on basis, shorter merus, carpus and propodus and with only two distal propodal setae. Dactylus and unguis together as long as propodus.

Pereopod 3 ( Fig. 8 C). Similar to pereopod 2.

Pereopod 4 ( Fig. 8 D). Slender, as long as pereopod 1, with apparent coxa. Basis nearly six times as long as broad. Ischium with two unequal setae. Merus less than twice as long as broad, with two short ventral spiniform setae. Carpus twice as long as merus, with three spiniform setae and a more slender rod-like seta. Propodus five times longer than broad and longer than carpus, with two ventro-distal spiniform setae and one longer terminal spiniform seta. Dactylus and unguis together 0.8 times as long as propodus, unguis with small ventral spine.

Pereopod 5 ( Fig. 8 E). Similar to pereopod 4.

Pereopod 6 ( Fig. 8 F). Similar to pereopods 4–5 but propodus with two long terminal spiniform setae and unguis with two minute spines.

Pleopod (not figured). Basal article longer than broad. Rami as long as or just longer than basal article; terminal setae longer than rami.

Uropod ( Fig. 7 E). About 0.75 times as long as pleotelson. Basal article shorter than broad. Exopod onearticled, half as long as article 1 of endopod, with one small distal seta and one long terminal seta. Endopod two-articled, articles of equal length, article 2 with five unequal distal and terminal setae.

Juvenile. Generally similar to above but pleopods only rudimentary, without setae, length 1.16 mm. Specimen lacks chelipeds.

Remarks. The two specimens recorded in the recent material closely conform to Kudinova-Pasternak’s description and seem to be unambiguously conspecific. The larger specimen is considered to be a preparatory male owing to its thick antennules and relatively well-developed pleon/pleopods compared to the original description (of a female).

Although Kudinova-Pasternak indicated ‘pereopod IV’ on her figure 15, this would have been equivalent to pereopod 3 in current usage; however what is drawn is representative of pereopods 4–5 (pereopods V–VI in earlier terminology). The pectination of the terminal propodal seta is actually quite slight and is not in conflict with Larsen’s account of L. longimanus , where a pectinate seta is present on pereopod 5. This Gulf of Mexico species has a more slender body, proportionately longer cheliped propodus, sparser pereopod setation and pleopods are lacking in females.

Distribution. The original record of F. rotundicauda was from the Kurile-Kamchatka Trench, 4945 metres, the present record was from the Japan Trench, 3146–3272 metres.

Figures

FIGURE 7. Forcipatia rotundicauda Kudinova-Pasternak, 1970. Preparatory male (?). A, habitus; B, pleon, lateral view; C, antennule; D, right cheliped; E, uropod. Scale bar = 0.5 mm for A and B, 0.22 mm for C-E.

FIGURE 8. Forcipatia rotundicauda. Preparatory male (?), A – F, pereopods 1 – 6 respectively. Scale bar = 0.25 mm for A-F.