Xenocheira xandrothrix, Hughes, 2017

Hughes, Lauren Elizabeth, 2017, Review of Xenocheira Haswell, 1879 (Crustacea: Amphipoda: Aoridae), Records of the Australian Museum 69 (4), pp. 223-236 : 233-236

Xenocheira xandrothrix sp. nov.

Figs 11 , 12

Holotype male, 6.4 mm, NTM Cr 011636, west of Elizabeth Reef , Cape Hotham, Beagle Gulf, Northern Territory, Australia, 12°04'S 131°20'E, 21 m, shale, 9 October 1993, coll. R. S. Williams, FV Kunmunyah (Beagle Gulf Marine Park Survey).

Type locality. West of Elizabeth Reef, Cape Hotham, Beagle Gulf, Northern Territory, Australia.

Etymology. From the Greek, xandros for sea monster and The sUffix thrix meaning hairy.

Description based on holotype male, 6.4 mm, NTM CR011636.

Head. Lateral cephalic lobes weakly truncate, anteroventral margin shallowly excavate to moderately recessed, anterodistal corner subacute. Antenna 1 peduncle article 1 pOsTeriOr marGin wiThOUT rObUsT seTae; flaGellUm UnknOwn. Antenna 2 unknown. Mandible molar triturative; accessory setal row with 8 setae; palp article 3 longer than 2, length 3.1× breadth, anterior margin straight with setae of two lengths. Maxilla 1 inner plate with 1 apical plumose seta; palp 2-articulate, article 2 broad, distal end with slender setae and 6 apical robust setae.

Pereon. Pereonites 1–2 without sternal process. Gnathopod 1 male coxa not produced anterodistally; basis broad, length 1.9× breadth; carpus compressed, length 0.8× breadth, 0.25× propodus length, posterior margin with dense long slender setae; propodus expanded, subovate, length 1.5× breadth, posterior margin with long slender setae, palm weakly obtuse, proximal shelf long, subquadrate, margin undulating, distal margin with narrow v-shaped sinus, defined by subquadrate corner with strong posterodistal spine reaching beyond dactylus, without post palmar robust seta; dactylus reaching beyond palm, posterior margin convex with proximal hump. Gnathopod 2 subchelate; basis proximally narrow, distally broad; merus 1.3× as long as broad; carpus 0.6× prOpOdUs lenGTh, anTeriOr marGin wiTh larGe flanGe, anterodistal end with double row of long slender setae, posterior margin with dense cluster of short slender setae; propodus rectilinear, length 4× breadth, anterodistal end with line of long slender setae, posterodistal end with dense cluster Of shOrT slender seTae, palm Transverse, less Than One fifTh The lenGTh Of pOsTeriOr marGin, wiThOUT rObUsT defininG seTa, dactylus short, recurved, reaching end of palm. Pereopods 5–7 basis margins with plumose setae; ischium, merus and carpus with patches of slender setae; propodus anterior and posterior margin with short robust and long slender setae; dactylus recurved, unguis present.

Pleon. Epimera 1–2 posterodistal corner rounded to subquadrate, ventral margin with plumose setae. Epimeron 3 posterodistal margin rounded with distal notch. Uropod 1 biramous; peduncle much longer than broad, distoventral interramal spine shorter than peduncle; rami subequal. Uropod 2 biramous; peduncle subequal to inner ramus length, with distoventral interramal spine less than half length of peduncle; inner ramus longer than outer ramus, apical robust setae of various lengths. Uropod 3 biramous, peduncle short, 0.6× rami length; rami subequal, with slender marginal and apical setae. Telson longer than broad, apically excavate with distal slender setae.

Remarks. Xenocheira xandrothrix sp. nov. and X. fasciata have the male gnathopod 1 palm obtuse, separating them from X. longisetosa and X. pirloti which have a transverse palm. Xenocheira xandrothrix sp. nov. has the male gnathopod 1 propodus with the distal spine extending beyond the dactylus which separates it from all other species in the genus. The gnathopod 1 dactylus is slender and has a proximal tooth on the posterior margin which further separates it from other Xenocheira species.

Distribution. Known only from type locality.

ACKNOWLEDGMENTS. Thank you to Roger Springthorpe for the image of X. fasciata . Joanne Taylor (MV), Sue Horner (NTM) and Steve Keable (AM) for speedy curation of material. I am grateful to Helen Stoddart and Alan Myers for critical review of the manuscript. This study was made possible through ABRS research grant RF 210-19.

Figures

Figure 11. Xenocheira xandrothrix sp.nov.holotype, 6.4 mm, NTM Cr011636, west of Elizabeth Reef, Cape Hotham, Beagle Gulf, Northern Territory (scale 0.1 mm).

Figure 12.Xenocheira xandrothrix sp.nov.holotype, 6.4 mm, NTM Cr011636, west of Elizabeth Reef, Cape Hotham, Beagle Gulf, Northern Territory (scale 0.1 mm).