“Austrodecus serratum, new species, Fig. 9
Material examined. Eltanin: 27-1974 (1 male (holotype, USNM 234600)), 16-1417 (1 female (paratype, USNM 234601)).
Distribution. This species is only known from two stations in the vicinity of Macquarie Island in 79-124 m.
Diagnosis. Of the A. glaciale section. Trunk compact, lateral processes closely crowded, short. Trunk with four large conspicuous dorsomedian tubercles. Ocular tubercle short, broad. Palp first segments with tall dorsal serrations, otherwise typical. Proboscis probably moderately short (broken off of both specimens). Legs short, robust. First coxae of first leg pair with single dorsodistal tubercle, other coxae of posterior leg pairs with two dorsodistal tubercles. Cement gland a low midventral cone less than half as tall as minimum segment diameter.
Description. Size moderately large for genus; length span 6.2 mm. Trunk compact, lateral processes closely crowded, little longer than half their diameters. Trunk with large, robust dorsomedian tubercles, each with 1-2 short setae. Ocular tubercle short, broad, without “tuck” or bend in posterior dorsal surface, eyes small, well pigmented. Abdomen moderately long, tapering distally, without conspicuous dorsodistal tubercle but with pair of short setae. Proboscis probably moderately short (distal half missing in both specimens).
Palps moderately short, first segment with scattered row of dorsal saw like serrations of varying sizes. Third segment about 0.6 length of first, without serrations but with several short dorsal and distal setae. Terminal two segments very short, terminal segment a rounded bulb slightly smaller than penultimate segment, both armed with field of short ventrodistal setae.
Ovigers typical, 6-segmented, terminal segment the largest, slightly curved, armed distally with 12-14 very short setae.
Legs short, robust, armed with few setae, major segments with typical long dorsodistal spine. First coxae armed with slender tubercles as long as coxal diameters; coxae pair on anterior legs with single dorsodistal tubercles, coxae pairs of second, third and fourth legs with two dorsodistal tubercles of equal size, all armed with 1-3 setae. Second coxae 0.3 longer than first and twice longer than third, armed with 3-4 dorsal papillae distal to midpoint. Third coxae with single broad short dorsal tubercle. Femora the longest segment, with short broad dorsodistal tubercle bearing a long spine and 4-5 short lateral setae. Cement gland pore at apex of small broad cone at midventral point of femora. Cone shorter than half femoral diameter. Second tibia short, shorter than propodi. Tarsus very short, with few ventral setae. Propodus broad, well curved, armed with 15-17 short sole spines with few flanking setae, several short dorsal and distal setae and broad short claw with slender auxiliaries almost half main claw length.
Measurements (holotype in millimeters). Trunk length (palp insertion to tip fourth lateral processes), 1.08; trunk width (across second lateral processes), 0.61; abdomen length, 0.28; third leg, coxa 1, 0.21; coxa 2, 0.32; coxa 3, 0.15; femur, 0.6; tibia 1, 0.53; tibia 2, 0.36; tarsus, 0.09; propodus, 0.41; claw, 0.14.
Etymology. The species name (Latin: serratus; toothed like a saw) refers to the combined effect of the toothed palp dorsum with the large tooth-like dorosmedian trunk tubercles.
Remarks. This species is similar to several compact closely crowded species having short ocular tubercles, dorsomedian trunk tubercles, and tall first coxae tubercles. What separates it from all other known species are the large size of the trunk tubercles, the tall evenly matched coxae tubercles on the posterior three pairs of legs, and the very small femoral cement gland cone of the male. The trunk tubercles have a broader base and are taller than in most species with similar tubercles, and the same height difference holds true for the coxae tubercles; they are taller than those of most species. Most species have first coxae tubercles on the fourth leg pair which are not evenly matched and with a posterior tubercle smaller than the dorsal one. Some species have only a single tubercle on the first coxae of the fourth legs, and the other tubercle is usually represented by a tiny papilla or sometimes nothing.
The cement gland cone, in the only male of the two specimens collected, is much smaller than the usual truncate cone, where one is present on the femur, and it is located at the ventral midpoint. Other species have such a small cone but it is usually more rounded and almost always located more ventrodistally on the femur. Of the species having a very small cement gland cone, where the male of the species is known, that of A. fagei is probably closest in shape, but it occurs more distally than the midpoint of the femur in that species. In A. gordonae, the small cement gland cone is not as tall and is also found more distally on the femur. The cone of A. simulans males is only slightly larger than that of the new species and is placed at almost the same locality of the midpoint, but the legs of A. simulans are much more slender and longer than those of A. serratum. There are also other differences between these two species.” (Child 1994b, p.71-73)
