Austropallene halanychi, Zehnpfennig & Mahon, 2023

Zehnpfennig, Jessica R. & Mahon, Andrew R., 2023, Austropallene halanychi sp. nov., a new species of sea spider (Pycnogonida, Callipallenidae) from the Ross Sea, Antarctica, ZooKeys 1185, pp. 163-180 : 163

Austropallene halanychi sp. nov.

Figs 2 , 3 , 4

Type locality.

Antarctica, Ross Sea, Ross Shelf, 570 m depth, 75°19'46.7"S, 176°59'06.3"W, collected via benthic trawl, 31 January 2013, RVIB Nathaniel B. Palmer (NBP12-10), A. Mahon leg.

Type specimen.

Holotype male preserved in ethanol, original label "Antarctica, Ross Sea, Ross Shelf, 570 m depth, 75°19'46.7"S, 176°59'06.3"W, 31 January 2013, J. Zehnpfennig and A. Mahon", NMNH 1548440"; handwritten label "Ch 226.1E".

Diagnosis.

The new species can be differentiated from all other described Austropallene species based on its much larger size, as well as its unique and distinctive chelifores. The chelifore claw of A. halanychi sp. nov. closes completely when the fingers converge, with no visible space remaining between the fixed and movable fingers. The movable finger of the chelifore claw is distinctly shorter than the fixed finger, and the chelifore fingers do not contain any denticles or notches on their inner surfaces.

Description of holotype (male).

Slender appearance, fully segmented trunk; neck distinct, large oblong ovigers attaching laterally; cephalic spurs present (Figs 2A-C , 3A, B ). Ocular tubercle (Figs 2A-C , 3B, C ) low, rounded, slightly inclined backwards, prominent distal papillae; four darkly pigmented eyes, anterior pair larger than posterior pair (Fig. 2A, I ). Lateral processes long, smooth, without spines. Abdomen short, conical, swollen distally, cleft anal opening. Proboscis (Figs 2A-C , 3B, D, E ) directed ventrally, broad at base, conical, slight mid-point constriction, distally tapering; mouth surrounded by setose wreath (Figs 2G, H , 3E ).

Chelifore (Figs 2D-F , 3B, D, F, G ), scape large and oblong, shorter than proboscis, directed slightly anteroventrally, slight tapering towards base; chelae long, 77.5% of scape length; tips of chela fingers blackened; fingers longer than one-half of palm length, fixed finger of chelifore concave with pointed tip. Movable finger 0.73 mm shorter than fixed finger, convex, with rounded tip. Chelifore fingers converge completely, no space present between fingers, denticles not present on inner surface of either finger. Two small conical outgrowths present where fingers of chelifore claw meet (Fig. 3B , arrow). Chelifore scape and claw contain small setae along dorsal and ventral sides.

Oviger 10-segmented (Figs 2O-R , 4A-G ), fifth segment longest, slightly curved, with prominent apophysis distally; oviger compound spines serrated, present on terminal four segments of the strigillis, strigilis formula: 20:20:18:18, with 2 prominent terminal spines. Some of the spines are broken off (Fig. 4E, F ).

Walking legs (Fig. 2J-N ), long, slender, sparse short spinules dorsally and ventrally on major segments; small conical tubercles and setae on first coxa. Femur shortest leg segment; tibia 2 longest segment; tarsus short, curved, small distal spine in line with heel spines; propodus curved, distinct propodal heel; five heel spines, relatively similar in size; many sole spines present; auxiliary claws absent, main claw extends nearly to heel. Gonopores and cement glands not observed.

Measurements (male holotype-mm).

Body length (anterior end of cephalon to posterior end of trunk) = 10.50; body width (right lateral process of leg 1 + width of trunk + left lateral process of leg 1) = 4.02; trunk width = 1.24; abdomen length = 6.97; ocular tubercle height = 0.39; proboscis length = 2.73; chela fingers = 2.61; main claw length = 3.37; scape = 2.39; oviger 5th segment = 4.18; 10th segment = 0.74; terminal oviger spines = 0.10; leg span 63.84mm (distance between terminal claws second pair of walking legs); walking legs 29.78 mm in length (from where first coxa meets lateral process to terminal claw on second pair of walking legs); 3rd walking leg coxa 1 = 1.23, coxa 2 = 2.60, coxa 3 = 1.17, femur = 6.69, tibia 1 = 6.85, tibia 2 = 7.89, tarsus = 0.32, propodus = 1.95, terminal claw = 1.39.

Etymology.

The species ( Austropallene halanychi , male genitive) is dedicated to Dr Kenneth M. Halanych, a mentor, colleague, and prolific marine invertebrate scientist whose commitment and dedication to the benthic marine systems in the Southern Ocean has provided a wealth of information related to biodiversity in the Antarctic system.

Figures

Figure 2. Austropallene halanychi sp. nov., male holotype A side view (scale) B dorsal view C front view, note cephalic spurs D dorsal view of opened chelifore claw; note absence of denticle and conical outgrowth at base of fixed and movable fingers E dorsal view of chelifore claw F ventral view of chelifore claw; note conical outgrowth G dorsal view of proboscis with setose wreath H setose wreath around proboscis I dorsal view of eyespot J third walking leg K first coxa of third walking leg L side view of second coxa of third walking leg M propodus of walking leg N tubercles and spines on walking legs O ovigerous leg of male P strigilis of ovigerous leg Q 10 th segment of oviger; note terminal spines R serrated ovigerous leg spines (compound spines) on strigilis of ovigerous leg.

Figure 3. Austropallene halanychi sp. nov., male holotype A dorsal view B dorsal-frontal view; note shape, relative size, and black tips of chela fingers, cephalic spurs, and eye tubercle and eyes; note sharp conical outgrowths at base of fixed and movable fingers of chelifores (red arrow) C eye tubercle, top view D dorsal view of cephalic spurs, chelifore claws, and proboscis; note setose wreath on proboscis E setose wreath of proboscis F dorsal view of chelifore claws; note lack of space between chelifore fingers and small outgrowth (red arrow) G dorsal view of tip of chelifore claw; note presence of bristles along top of immovable finger.

Figure 4. Austropallene halanychi sp. nov., male holotype A oviger, entire B strigilis, close-up view showing compound spines on segments 7 - 10 C compound spines on segment 9 D compound spines on segment 9 E strigilis, side view, showing compound spines on segments 7 - 10 (some spines on segment 10 are damaged or missing) F segments 8 - 10 with compound spines, and segment 10 with two terminal spines G segment 10, top view, close-up, with two terminal compound spines.