“Cheilopallene gigantea, new species Fig. 5
Material examined. —E of Antarctic (Palmer) Peninsula. Weddell Sea. Antarctica. off Larsen Ice Shelf, 66°28'S, 57°26'W, 581-610 m, coll. Hero, sta 3-28D. 17 Aug 1970, holotype male, USNM 233609.
Description. —Size extremely large for genus, leg span 57.6 mm. Trunk moderately robust, segments slightly inflated, glabrous. Lateral processes short, less than twice as long as diameters, separated by less than their diameters, armed with 2-3 dorsodistal small setae. Neck moderately long, tapering anteriorly toward greatly inflated anterior at chelifore and proboscis insertion, armed with 4 dorsodistal setae over chelifore insertion. Ocular tubercle low, only slightly taller than width at base, tip rounded, eyes large, lightly pigmented, sensory papillae tiny. Tubercle placed toward posterior of cephalic segment, just anterior to first lateral processes and slightly posterior to midpoint ofoviger insertion bulges. Proboscis typical, fairly short, proximal half cylindrical, inflated distally, tapering to moderately large petal-like lips, each semirectangular, covered with closely packed pilose setae. Abdomen short, extending barely to tip of 4th lateral processes, armed with 4-5 short distal setae.
Chelifores massive, single segmented scapes very large in diameter. Chelae palm almost globular, fingers typical, shorter than palm. with uneven ridges and bumps as dentition. Scape armed with few short setae, chelae with many short setae on distal palm and fingers.
Oviger fully formed, of 10 segments with strigilis. Third segment slightly longer than first two combined in length. Third through sixth segments armed with rows of short ventral and dorsal setae. Fourth and fifth segments slightly curved, fifth slightly longer than fourth, armed with dorsodistal tubercle not quite as tall as segment diameter, armed with 5-6 short setae. Sixth segment with dorsal and ventral fringe of short setae increasing in numbers distally. Strigilis segments subequal in length, fully formed, armed with few short ectal setae, row of endal denticulate spines in formula 19:19: 18:16. and terminal claw slightly over half length of terminal segment, bearing 23-24 short closely spaced endal setae. Denticulate spines of 2 lengths; proximal forms shorter with 3 proximolateral serrations and many tiny crenulations distally, and distal spines, longer, with 3-4 lateral serrations grading into many fine crenulations distally. Egg size slightly greater than maximum diameter of widest segment.
Legs moderately setose with short setae, none as long as segment diameter, increasing in numbers on major distal segments. Tibia 2 longest segment, femur and tibia 1 subequal, second coxae slightly longer than first and third combined. Femur with 4 tiny slightly raised cement gland pores evenly spaced along length of segment. Tarsus short. about 0.22 length of propodus. armed with tuft of short ventral setae. Propodus slightly curved, without marked heel, with 4 large heel spines increasing in size distally from proximal smallest. Sole armed with many very short setae and short flanking setae Propodus tip slightly projecting. Claw long, slender, slightly curved. about 0.7 as long as propodus. Without auxiliary claws.
Measurements (in mm).—Trunk length (chelifore insertion to tip 4th lateral processes) 5.46; trunk width (across 2nd lateral processes) 3.08; proboscis length 1.62; abdomen length 0.58; third leg, coxa 1 1.02; coxa 2 2.62; coxa 3 1.22; femur 5.38: tibia 1 5.46; tibia 2 7.32; tarsus 0.48; propodus 2.15; claw 1.62.
Distribution. —Known only from the type locality, off the Larsen Ice Shelf on the cast side of the Antarctic (Palmer) Peninsula, Antarctica, in 581-610 m.
Etymology. —This giant (Latin: gigantea) new species is named for its size which is at least four times larger than any other known species of the genus.
Remarks. —The enigmatic genus Cheilopallene now contains four known species, including this new species; C. breviehela Clark (Maldives). C. clavigera Stock (U.S. Virgin Islands). and C. trappa Clark (Snares Islands, New Zealand). Three of these four species have normal ten-segmented ovigers with a strigilis bearing denticulate spines, while the type of the genus, C. clavigera (Stock, 1955:230-233), has an elongate fifth oviger segment that is clubbed distally. A tiny sixth segment extends beyond this swollen tip and represents all that remains of the strigilis. A series of males of this species must be examined to discern whether or not this is the natural state of the oviger.
This abbreviated oviger appears also to be the natural form in many specimens of another genus erected to emphasize this character. Pushkin (1974:938-940) removed Hodgson's (1915) Pallenopsis spicata from that genus and placed it in his genus Clavigeropallene, because it bears seven oviger segments in the male (instead of the usual ten), with the sixth broadly clubbed, and lacks a strigilis. This oviger modification appears to he neither a localized distributional feature nor a monotypic malformation due to damage and subsequent regeneration in a number of specimens (Hodgson 1915, Cal man 1915, Hodgson 1927, Gordon 1938). Instead, it is probably another apomorphic character in a group of genera that are undergoing rapid change and dissemination from areas of origin in the Southern Hemisphere. It appears that many and perhaps even the majority of genera (now numbering 24 or 25) in the family Callipallenidae had their origins in that hemisphere and have reached their present known distribution patterns through unknown means of transport. Without a planktonic larval stage or other means of active transport many species are localized or endemic and their dissemination in the oceans of the world is probably quite slow. The distribution of most callipallenid genera is poorly known to fragmentary at best, as is true for most pycnogonids, but the majority of species in these genera have been taken in Southern Hemisphere localities or at least near the equator in Indo-Pacific localities. From this distributional evidence, Australia and South Africa are the two focal points of dissemination among the majority of genera in this family, with Antarctic polar seas containing a wealth of species with characters crossing many generic lines. This inevitably points toward a Gondwanaland land mass for the origins of the protofamily that lead to the many genera now extant, but without a valid geological record to support such an hypothesis, it must remain conjecture.
This species differs from the three others known, in addition to its very much larger size, by having much shorter lips covered by a thick coat of setae. In the other species, the lips are narrower, longer, glabrous, and described as 'petal-shaped'. The proboscis and its parts are very characteristic in almost all pycnogonids and have long served as one of the valid diagnostic features. The lips of this new species are not typical of others in the genus which have small glabrous triangular lips, but are more characteristic of other species in genera having lip fringes or heavily setose oral surfaces such as some of the Parapallene, Pallenoides, and Pseudopallene species. The lip characters arc species-specific and do not always serve as diagnostic characters for the genera in this family.
The chelae of the four species are remarkably similar and all have the uneven endal linger surfaces. The movable finger appears to fit into a pseudosocket toward the tip of the immovable finger, but the use of such an arrangement for feeding or defense can only be conjectural.” (Child 1990, 912-914)
