Nymphon tricuspidatum, Anna, Soler-Membrives, 2011

Anna, Soler-Membrives, 2011, A new species of Nymphon Fabricius, 1794 (Pycnogonida: Nymphonidae) from northern Spain, Zootaxa 2798, pp. 31-36 : 31-34

Nymphon tricuspidatum n. sp.

Material examined. Galician Atlantic waters: 1 male, holotype (registration number Pyc 124DA), 2 males (2 ovigerous and 1 without eggs), 2 gravid females, 4 juveniles, 9 postlarvae, paratypes (Pyc125 to 128DA). EBS 600-03 station. 596–610 m depth. 43º48.59’N, 8º51.45’W. Collected by an epibenthic sledge during the DIVA- ARTABRIA cruise. Sand and rock bottoms. 18/9/2003.

Le Danois Bank (El Cachucho, Biscay Bay, NE Atlantic). 1 male without eggs and 1 juvenile, paratypes (Pyc 129CA). 574 m depth. 44º05.85’N, 4º51.08’W. Collected by suprabenthic sledge. Fine sand and mud bottoms. 17/ 10/2003.

Description of holotype (ovigerous male, ex. Nº 4, DIVA-ARTABRIA cruise). Trunk slender and elongated in outline, glabrous and completely segmented. T- shaped cephalon. Lateral processes separated by equal or more than their own diameter; smooth, without tubercles or setae, slightly longer than broad. Abdomen directed obliquely upwards, bearing only 2 distal setae. Abdomen reaching to half of second coxa from fourth leg.

Proboscis rather robust and short—somewhat shorter than scapus—inclined 45º ventrally, 2 times longer than its diameter. Cylindrical, distally bluntly rounded, with a constriction near to the distal region.

Ocular process high and tricuspidate (derivatio nominis), slightly forwardly inclined, situated at the posterior of cephalon, at level of ovigerous implantation. Eyes feebly pigmented, almost transparent.

Long and robust cheliphores. Cheliphore implantation laterally with respect to frontal cephalon, forming an angle of 80º with respect to the proboscis longitudinal edge. Chela slightly longer than scape. Chela fingers longer than palm. Immovable finger of the chela cutting edges bearing 21 major teeth (with a few short setules) and movable finger with 31 teeth. Between the major teeth there are 4–6 smaller denticles. The juvenile specimens have fewer teeth than adults.

Palp 5-articled; 2nd article the longest, 3rd and 5th article about equal in length; distal article only slightly longer than fourth; breadth of two distal articles 0.1 mm, especially setose.

Oviger 10-articled; 5th article the longest, slightly curved, with a distal apophysis bearing some setae; 4th article straight, smooth, with a proximal lump. Articles 7–10 (strigilis) with 16 compound spines each with 2–3 pairs of denticles, distributed in the formula 5: 4: 3: 4. Distal claw armed with 6 slender, similar and curved teeth.

Legs relatively slender, 5 times as long as trunk. Coxa 2 nearly three times as long as coxa 1 or coxa 3, which are similar in length. Femur slightly less setose than tibia. Setae short and long, the latter longer than the diameter of article. Tibia 1 slightly longer than femur, both straight. Tibia 2 the longest segment, feebly curved. Tarsus slightly shorter than propodus; both segments slender and with spinose ventral margin. Main claw half length of propodus; no auxiliary claws. Males have 2–3 cement gland tubes situated dorso-medially on femur, sparsely distributed, or in pairs close together. Coxa 2 of legs 3 and 4 with ventro-distal round genital process.

Body and oviger of females similar to males, except lacking proximal lump of the fourth ovigeral article. Female gonopores located on the second coxae of the four pairs of legs.

Remarks. The greenish holotype was bearing a ball with 8 eggs glued to the right oviger. Juveniles studied have a lower number of teeth on the movable and immovable fingers of the chela, and fewer strigilis denticles.

Measurements of holotype (mm). Trunk length: 2.4; trunk width: 1.4; abdomen length: 0.6; Proboscis: length: 0.8; width: 0.4; Cheliphore: total length: 2.2; scape: 1.0; chela: 1.2; fingers: 0.9; palm: 0.3; Palp: total length: 2.1; art.1: 0.1; art.2: 0.8; art.3: 0.5; art.4: 0.3; art.5: 0.5. Second leg: total length: 12.2; coxa 1: 0.3; coxa 2: 1.0; coxa 3: 0.3; femur: 2.5; tibia 1: 2.8; tibia 2: 3.3; tarsus: 0.7; propodus: 0.9; claw: 0.4. Oviger length: 3.7.