Akanthophoreus

Bird, Graham J, 2007, Family incertae cedis *, Zootaxa 1599, pp. 121-149 : 138-139

Akanthophoreus sp.KK#3

Figures 13–14

Material examined. 1 non-ovigerous female (or early preparatory male?), 2.96 mm, station TD-8, 39º15.54’– 39º17.01’N 144º45.37’– 144º42.46’E, 5762–5733 metres, 4 m ORE beam trawl, 29 September 2001. 1 preparatory male, 2.56 mm, station TD-7, 38°47.93’– 38°45.87’N 144°08.07’– 144°07.89’E, 7340–7433 metres, 30 September 2001.

Remarks. This is a fairly slender species, 7.2–7.9 times as long as broad, but with a relatively short cephalothorax compared to other Akanthophoreus species ( Figs 13 A). It is further characterized by thick, pectinate, antennular setae ( Fig. 13 D), an elongate uropod basal article ( Fig. 13 G) as seen in Paraleptognathia brachiata ( Hansen, 1913) , a cheliped carpus without shield ( Fig. 14 A), a stout pereopod 1 with very long meral and carpal pectinate spiniform setae ( Fig. 14 B), these two articles also with a thin dorsal seta, and pereopods 4–6 ( Fig. 14 C) with long propodal pectinate setae.

Distribution. Japan Trench, 5733–7433 metres.

Largely because of these characters, this species is only provisionally and tentatively assigned to Akanthophoreus , as it may represent a separate, but closely related, genus: the most similar described species appears to be the equally hadal Biarticulata parabranchiata ( Kudinova-Pasternak, 1977) from the Palau Trench, 7000–7170 metres. Another extremely similar, but undescribed species, has been recorded from the abyssal NE Atlantic (as ‘ Leptognathia brachiata Hansen, 1913 ’) by Holdich & Bird (1985) and which has Akanthophoreus -like mandibular molars, not dissimilar to those of B. parabranchiata .

Figures

FIGURE 13. Akanthophoreus sp. KK # 3. A, non-ovigerous female (?), habitus; B, pleon lateral view, pleopods omitted for clarity; C – D, antennule, dorsal and lateral view (setae omitted for clarity); E, uropod; F, preparatory male, habitus; G, antennule, lateral view, (setae omitted for clarity). Scale bar = 1 mm for A, B and F, 0.38 mm for E, 0.25 mm for C, D and G.

FIGURE 14. Akanthophoreus sp. KK # 3. Non-ovigerous female. A, cheliped; B, pereopod 1; C, pereopod 5. Scale bar = 0.33 mm for A, 0.25 mm for B and C.