Nymphon ludovici, Sabroux & Hassanin & Corbari, 2022

Sabroux, Romain, Hassanin, Alexandre & Corbari, Laure, 2022, Sea spiders (Arthropoda: Pycnogonida) collected during the Madibenthos Expedition from Martinique shallow waters, European Journal of Taxonomy 851 (1), pp. 1-141 : 59-63

Nymphon ludovici sp. nov.

urn:lsid:zoobank.org:act:53F8FAE5-3380-479C-A5AE-8C6B30CAC9A5

Figs 12–13

Nymphon sp. 3 – Sabroux et al. 2019b: 1525, 1531, tab. 1, fig. 3.

Material examined

Holotype MARTINIQUE • ♂ ov. carrying larvae; Les Anses-d’Arlet; 14°29.6ʹ N, 61°05.5ʹ W; depth 10–26 m; 7 Sep. 2016; st. AR050; MNHN-IU-2016-835/ MK411150 .

Paratypes MARTINIQUE • 1 ♀; Canal de Ste Lucie ; 14°22.7ʹ N, 60°51.6ʹ W; depth 65 m; 11 Sep. 2016; st. AD222; MNHN-IU-2016-836/ MK411151 • 1 ♂; Passe du Marin ; 14°26.6ʹ N, 60°54.3ʹ W; depth 15 m; 9 Sep. 2016; st. AB058; MNHN-IU-2016-837/ MK411152 • 1 ind. (sex indet.); Passe du Marin ; 14°26.7ʹ N, 60°54ʹ W; depth 19– 15 m; 10 Sep. 2016; st. AB060; MNHN-IU-2016-558 • 1 ♂; Grande Anse d’Arlets ; 14°29.9ʹ N, 61°05.4ʹ W; depth 28 m; 7 Sep. 2016; st. AB157; MNHN-IU-2016-561 • 1 ♂; same collection data as for preceding; MNHN-IU-2016-562 • 1 juv.; same collection data as for preceding; MNHN-IU-2016-1274/ MK411094 • 1 juv.; same collection data as for preceding; MNHN- IU-2016-1323/ MK411099 • 1 ♂ ov. carrying larvae; Presqu’Île de la Caravelle ; 14°44.1ʹ N, 60°50.8ʹ W; depth 29 m; 18 Sep. 2016; st. AS 253; MNHN-IU-2016-1107 • 1 ♀; same collection data as for preceding; MNHN-IU-2017-219 • 1 juv.; Vétiver ; 14°37,8’N- 61°07,7’W; depth 25 m; 8 Sep. 2016; st. AB161; MNHN-IU-2016-1118/ MK411054 • 1 ♂ ov.; Presqu’Île de la Caravelle ; 14°48.4ʹ N, 60°52.8ʹ W; depth 23–25 m; 20 Sep. 2016; st.AB197; MNHN-IU-2016-1317 • 1 ♂; N Presqu’Île de la Caravelle ; 14°51.9ʹ N, 60°50.7ʹ W; depth 57 m; 19 Sep. 2016; st. AD247; MNHN-IU-2017-3500 .

Etymology

From the Latin first name Ludovicus , - i, (masc., 2 nd decl.), from which the French name Louis originates. The species is named after the Fort Saint-Louis naval base in Fort-de-France, Martinique, where the Madibenthos crew was warmly welcome and hosted for the whole expedition.

Description (holotype, ♂, MNHN-IU-2016-835)

BODY. Medium size, slender species. Trunk completely segmented, cuticle smooth. No dorsomedian ornamentation. Ocular tubercle positioned anteriorly to 1 st lateral processes; about as tall as its diameter, rounded, slightly bent backward, with wide, slightly bifid rounded tip carrying lateral sense organs distally; four pigmented eyes. Preocular neck long, about 3 times as long as wide, markedly segmented at base. Oviger base well separated from 1 st lateral processes. Lateral processes well separated by about twice their diameter between 1 st and 2 nd, about 1.5 times between 2 nd and 3 rd, and about their diameter between 3 rd and 4 th; lateral processes without ornamentation.

PROBOScIS. Robust, with distal swelling on 3 antimers, bearing a few setae around mouth. Proboscis reaching about distal part of chelifore scape in lateral view.

ABDOMEN. Small, rounded with pointed anus, directed diagonally. No basal articulation.

CHELIFORE. 2-articled, long, reaching beyond proboscis. Scape 1-articled, about 5 times as long as wide, with dorsal setae on distal part, peculiarly on distal margin. Chela large, palm ornamented with a few setae, longer than fingers. Fingers crossing at tip, carrying bifid teeth plus simple teeth at base. 16 bifurcate teeth plus 3 simple teeth on imovable finger, 14 bifurcate teeth plus 2 normal teeth on movable finger.

PALP. 5-articled. 1 st article shortest, shorter than wide, glabrous. 2 nd article longest, about 4/3 length of 3 rd or 5 th, more than 10 times as long as wide. 3 rd article about 7 times as long as wide, with several setae on ventrodistal margin. 4 th article about 1.5 times as long as wide, covered with ventral setae. 5 th article of about same size as 3 rd, about 6 times as long as wide, covered ventrally with setae.

OvIGER. 10-articled, slender, 1 st and 2 nd articles as long as wide, with scarce setae mostly on last 5 articles, 3 rd article less than 5 times as long as wide. 4 th article about twice as long as 3 rd. 5 th article longest, more than 1.5 times as long as 4 th, slightly curved, inflated distally. 6 th article about half as long as 4 th. 7 th article about 0.6 times as long as 6 th. 8 th, 9 th and 10 th articles shorter than 7 th, subequal. Strigilis formula 15:12:13:13. Strigilis spines compound, carrying many lateral teeth. On 7 th to 9 th articles proximalmost compound spine shortest and oblong, median spines lanceolate and longer than proximal ones, distalmost ones spatulated, with most basal teeth of compound spines conspicuously broader than distal teeth. Intermediate position spines roughly intermediary in shape. On 10 th article, all spines but two distal ones round to oblong and short, two distal spines spatulated with basal teeth of spines conspicuously broader than distal teeth, distalmost spine longest. Terminal claw about ⅔ of 4 th strigilis article length.

LEGS. Long and slender, with scarce setae. Coxae 1 and 3 subequal, about 1.5 times as long as wide. Coxa 2 more than twice as long as coxae 1 and 3 together. Femur about 12 times as long as median width, with one row of cement glands and cement gland pores on ventral surface, 46 counted on 4 th leg. No cement gland tube. Tibia slightly longer than femur, about 12 times as long as median width. Tibia 2 longest, about 1.5 times as long as femur and 22 times as long as median width. Tarsus medium-sized, about 3 times as long as wide, trapezoid, with one ventrodistal spine. Propodus straight, about 0.2 times as long as tibia 2 and 6 times as long as broad, no basal spine; sole with 8 spines and setae. Main claw curved, short, less than ¼ of propodal length. Auxiliary claws curved, slightly longer than main claw. Both auxiliary claws and main claw with denticles on inner surface.

MEASUREMENTS (mm). Trunk 2.08; abdomen 0.16; proboscis 0.87; chelifore scape 0.98; chela palm 0.62; chela fingers 0.36; coxa 1 0.26; coxa 2 1.1; coxa 3 0.31; femur 1.97; tibia 1 2.15; tibia 2 2.83; tarsus 0.23; propodus 0.71; main claw 0.18; auxiliary claw 0.22.

Sexual dimorphism

Available female poorly preserved. Oviger articles shorter than in males, no distal inflation of 5 th article. Females chela palm not as wide as in males ( Fig. 13 ).

Individual variability

Number of teeth on chela fingers variable, up to 18 teeth on movable finger and 16–19 on imovable finger in investigated specimens. Strigilis formula variable, 11–18 per strigilis article, with generally more spines on 7 th oviger article. Teeth of 10 th oviger article either spatulated (e.g., MNHN-IU-2016-835) or lanceolate (e.g., MNHN-IU-2016-837), sometimes within same barcode cluster.

Remarks

Nymphon ludovici sp. nov. can be discriminated from other aequidigitatum -group species with the combination of the four following characters: (i) the preocular neck is long, (ii) the tarsus is short, (iii) the lateral sense organs on the ocular tubercle tip are low and the ocular tubercle tip is not bifurcate; and (iv) the main and auxiliary claws are subequal in length. The closest species are the Japanese N. plectrum Takahashi et al., 2012 , which presents much more setose legs, longer leg setae and lateral sense organs well separated on the ocular tubercle, and N. floridanum Hedgpeth, 1948 from the Caribbean, which has no segmentation at the base of the preocular neck.

We were not able to infer whether the segmentation at the preocular neck base corresponds to a mobile articulation. This feature is shared with a number of species from the aequidigitatum complex ( Child 1988b; Takahashi et al. 2012): N. adense Müller, 1989 , N. aldabrense Child, 1988 , N. giraffa Loman, 1908 , N. micronesicum Child, 1982 and N. plectrum Takahashi et al., 2012 . Some other species of the aequidigitatum -complex show a constriction at the same location of the ocular neck that does not seem to be a segmentation, e.g., N. natalense Flynn, 1928 (see Flynn 1928). This species is divided into two clusters based on DNA barcoding data (intracluster p-distance = 0–0.026, intercluster p-distance = 0.104 –0.111) ( Sabroux et al. 2019b). Since no morphological character was found to support their separation, the two clusters corresponding to group 1 (holotype MNHN-IU-2016-835 and paratype MNHN-IU-2016-837) and group 2 (paratypes MNHN-IU-2016-562, -836, -1118, -1274 and -1323) (Appendix), were described as the same species.

The species was collected on both the Atlantic and Caribbean coasts.

Distribution

Only known from type locality.

Depth range

15– 57 m.

Figures

Fig. 12. Nymphon ludovici sp. nov., holotype, ♂, MNHN-IU-2016-835. A. Body, dorsal view. B. Body, lateral view (same scale as A). C. Ocular tubercle, lateral view.D. Ocular tubercle, frontal view. E. Palp. F. Chelifore, with close-up of two bifid teeth. G. Oviger. H. Strigilis. I. Pointed teeth of strigilis. J. Fourth leg. K. Tarsus and propodus of fourth leg. L. Propodal claws.

Fig. 13. Nymphon ludovici sp. nov., paratype, ♀, MNHN-IU-2017-219. Chelifore.