Propallene saengeri Staples, 1979

Arango, Claudia P., 2003, Sea spiders (Pycnogonida, Arthropoda) from the Great Barrier Reef, Australia: new species, new records and ecological annotations, Journal of Natural History 37 (22), pp. 2723-2772 : 2742

Propallene saengeri Staples, 1979 Propallene saengeri Staples, 1979: 90–93 , figure 2d, figure 4; 1982: 456–457; Nakamura and Child, 1983: 61–62 (key).

Material examined. Rowes Bay, intertidal in C. prolifera , 17 August 1998, three W with eggs, two X, five post-larvae; 3 November 1998, one W, two X, two postlarvae; 1 June 2000, one W, two W with eggs, two X, two juveniles. Picnic Bay , intertidal amongst C. vagabunda (L.) van de Hoek , 3 October 1998, four W, one X. Turtle Bay , 4 May 2000, one W with eggs and protonymphs.

Description. Trunk 0.8 mm in length, crurigers not touching but separated by less than half their own diameter, neck almost twice long as wide at the middle. Ocular tubercle posterior on the neck; abdomen horizontal as a continuation of the trunk, tapering towards the end; proboscis short, cylindrical. Scape one-segmented, fingers curved, immovable finger with four teeth and movable with four or five smaller teeth. Palps in males only, very short, two-segmented, with four or five long distal setae. Setiferous apophysis on the fifth segment of oviger in males, two recurved long spinules in the seventh segment, formula 7:6:6:6, distal spine multifurcated. Legs slender, femur the longest segment, short setae in all coxae and two spines dorsally in the tarsus. Propodus with heel, with two crenulate spines, sole with eight or nine spines; auxiliary claws absent. Cement glands numerous short ducts placed ventrally in femur and tibiae (four to six in femur, four in tibia 1 and three to four in tibia 2).

Distribution. Propallene saengeri was described from the mouth of the Calliope River in south Queensland (Staples, 1979). It was found on soft mud upstream at 1– 2 m. This is the second record for the species in Australia. It has been found once in shallow waters of Sagami Bay, Japan (Nakamura and Child, 1983).

Remarks. There are three species of the genus known for Australia; P. cyathus Staples, 1979 and P. vagus Staples, 1979 have been recorded from south-eastern Australia. Propallene saengeri is differentiated by its very small size and the greater length of the second palp segment (six times longer than wide). Propallene saengeri was found in relatively high abundance in some of the samples at Rowes Bay and in one sample at Turtle Bay in the alga C. prolifera . Some ovigerous males collected had the protonymphs attached. This is another species of Callipallenidae in which larval development occurs in the ovigers of males. This feature could provide an opportunity for genetic and ecological studies of marine invertebrate species with very limited dispersion phase and potential high rates of speciation (King, 1973).