Nymphon enteonum, Child, 2002

Child, C. Allan, 2002, Some Pycnogonida from the Eastern (Hasa) District of Saudi Arabia, Journal of Natural History 36 (15), pp. 1805-1821 : 1817-1819

Nymphon enteonum new species (gure 4)

Material examined. Saudi Arabia: ARAMCO stations: Sta. 730214G/1, Tarut Bay , 14 February 1973 (one juv. paratype, USNM 234730 ) ; Sta. 730319 A/3, Tarut Bay , 19 March 1973 (one with eggs, holotype, USNM 234728 , two with eggs, one, paratypes, USNM 234729 ) .

Other material. Saudi Arabia: Northern Area Baseline Survey ( NABS) stations: Sta. 4G-1, 10 September 1981 (one damaged); Sta. 6G-3, 9 April 1985 (one) .

Tarut Bay stations: Sta. 1TG-1, 5 May 1985 (two); Sta. 1TG-3, 5 May 1985 (one with eggs, one juv.); Sta. 8TG-1, 12 May 1985 (one ovig.); Sta. 8TG-3, 12 May 1985 (one ovig., one); Sta. 14TG-1, 14 May 1985 (two).

Distribution. The new species is known from its type locality, Tarut Bay, and from other scattered localities in Saudi northeastern coastal areas in 0– 10 m. It was not commonly found at most regularly sampled sites.

Description. Size small but average for shallow-water species of this genus; leg span 12.5 mm. Trunk glabrous, fully segmented, lateral processes separated by about their own diameters, from 1.0 to 1.5 longer than their diameters. Neck moderately short, area of chelifore insertion narrower than average, oviger implantation at posterior of neck, ventral to ocular tubercle. Ocular tubercle low, as wide as tall, eyes well pigmented, anterior pair twice size of posterior pair. Proboscis short, only as long as short chelifore scapes, cylindrical, distally tapering to small oral surface. Abdomen short, tapering along its entire length, armed with four tiny dorsal setae.

Chelifore scapes short, slightly curved inward, armed with few short lateral and distal setae. Chelae palms very short, half length of ngers. Fingers mostly straight, only nger tips curved, overlapping, both armed with eight large teeth as long or longer than their adjacent nger diameter, those of immovable nger slightly recurved. Palm and immovable nger with few short setae.

Palps moderately short, slender, distal segments armed with few ventral and distal setae. Third segment longest, about 1.2 times longer than second, fourth and fth segments subequal, combined length of both shorter than third.

Oviger segments 4 and 5 moderately curved, fth armed with row of short lateral setae. Sixth segment shorter than seventh, armed with few short lateral setae. Strigilis segments increasingly shorter distally than preceding, armed with denticulate spines with two lateral lobes per side in the formula 8: 6: 5: 6: with ve small teeth on slightly curved terminal claw. Claw not as long as terminal segment. Oviger with eggs: egg size only about 1.5 times oviger diameter.

Legs slender, moderately long, armed with few dorsal and ventral short setae. Second tibiae the longest segment. Tarsus cylindrical, moderately short, almost half propodal length, armed with few short sole setae. Propodus slender, slightly curved, with few sole setae like those of tarsus. Claw short, slightly curved, less than 0.25 length of propodus, auxiliaries slender, as long as main claw. Cement glands and openings not found.

Female character diVerences very few. Oviger fth segment shorter, as would be expected. Ovigerous female femora not greatly expanded and general size of specimens little greater than males.

Measurements of holotype in mm. Trunk length (chelifore insertion to tip fourth lateral processes), 1.39; trunk width (across second lateral processes), 0.64; proboscis length, 0.33; abdomen length, 0.2; third leg, coxa 1, 0.23; coxa 2, 0.61; coxa 3, 0.29; femur, 1.13; tibia 1, 1.23; tibia 2, 1.46; tarsus, 0.26; propodus, 0.6; claw, 0.14.

Etymology. The species name (Latin: enteon, meaning armed, bearer of ghting gear, with weapon) refers to the gaping chelae with teeth which are larger than usually found in most species of this genus.

Remarks. This species, like several others recently described from shallow waters and reefs, is rather plain-looking and without distinctive characters. The large chelae teeth become almost its only distinctive feature other than the short main claw and unusually long auxiliaries in relation to main claw length. One of the interesting characters of some of these shallow water reef species of Nymphon is the relatively reduced size of their anterior parts (everything anterior to the neck) in relation to the rest of the trunk when compared with most other Nymphon species. It remains unknown whether or not this has any taxonomic signi cance.