Tanystylum boucheti, 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 : 26-28

Tanystylum boucheti sp. nov.

urn:lsid:zoobank.org:act:E1915AAA-F3A8-496C-AF45-3BD9355DEB5E

Fig. 5A–H nec Tanystylum hummelincki Stock, 1954 – Sabroux et al. 2019b (pro parte): tab. 1, figs 3, 5.

Material examined

Holotype MARTINIQUE • ♂ ov.; Baie du Robert; 14°42ʹ N, 60°53.8ʹ W; depth 2 m; 24 Sep. 2016; st. AB452; MNHN-IU-2016-1074/ MK411045 .

Etymology

Latinized name, 2 nd decl. (masc.), genitive singular. The species is named after Philippe Bouchet, head of the Madibenthos Expedition.

Description (holotype, ♂, MNHN-IU-2016-1074)

BODY. Trunk completely unsegmented, discoidal; cuticle granular. No dorsomedian ornamentation. Ocular tubercle lower than abdomen, about as tall as base width, with two acute terminal tips, one large anteriorly and one smaller posteriorly, and 2 small lateral sense organs laterally, and carrying four large pigmented eyes. Cephalon with two low lateral tubercles at anterolateral margin. Low dorsal rising at base of abdomen. Lateral processes about as long as wide, jointed; 1 st lateral process with one submedian tubercle, 2 nd and 3 rd lateral processes with two dorsolateral tubercles on distal margin, 4 th lateral process with one anterior tubercle on distal margin. Lateral process tubercles carrying one short seta.

PROBOScIS. Conical in dorsal view, rounded proximally and conical distally in lateral view, with blunt tip, about as long as two anterior trunk segments.

ABDOMEN. Vertically oriented, higher than ocular tubercle, not reaching beyond lateral processes. Setae present on distal part. No basal segmentation.

CHELIFORE. 1-articled, composed of one elongated knob with two distal setae.

PALP. 6-articled, with setae on all articles except 1 st article. 1 st article shortest, wider than long. 2 nd article about 2.5 times as long as wide. 3 rd article shorter. 4 th article longest, about 2.5 times as long as 2 nd article. 5 th article about as long as wide, with ventral setae. 6 th article about 4 times as long as wide.

OvIGER. 10-articled with scarce setae. 1 st article as long as wide. 2 nd article about twice as long as wide. 3 rd article about 1.5 times as long as wide. 4 th article about twice as long as 3 rd. 5 th longest, curved. 6 th article 4/3 as long as wide. 7 th article about as long as wide, presenting one distal low spur carrying long setae. 8 th and 9 th articles subequal. 10 th article shortest. Strigilis spines simple on articles 7 th to 9 th, compound on 10 th article. Strigilis formula 2:1:1:2.

LEGS. Stout and nodulous, with scarce small setae. Coxa 1 shorter than wide, carrying 3 distal tubercles: anterodistal tubercle bifid, dorsomedian and distal tubercles simple, each tubercle with one short seta at tip. Coxa 2 longer than coxa 1 or 3. Coxa 3 as long as broad, with ventral setae. Femur stout, about twice as long as wide, with one elevated, dorsdistal cement gland tube. Tibia 1 and tibia 2 with large rounded tubercles and long setae on dorsal surface. Femur, tibia 1 and tibia 2 subequal. Tarsus trapezoid, short, about as long as wide, carrying one large spine and setae on ventral surface. Propodus stout and curved, with 3 large basal spines, and small spines on distal half of sole. Main claw curved, about ⅔ as long as propodus. Auxiliary claws present, about half as long as main claw.

MEASUREMENTS (mm). Trunk 0.61; abdomen 0.20; proboscis 0.33; chelifore 0.12; coxa 1 0.12; coxa 2 0.26; coxa 3 0.10; femur 0.42; tibia 1 0.40; tibia 2 0.45; tarsus 0.05; propodus 0.35; main claw 0.21.

Sexual dimorphism

Female unknown.

Remarks

The closest species to Tanystylum boucheti sp. nov. is T. isthmiacum Stock, 1955 ; we distinguish this species from the Stock’s species by its vertical abdomen, the presence of bifid tubercles at the dorsal margin of coxae 1 rather than rounded, and its more pronounced dorsal tubercles on the margin of the lateral processes ( Müller & Krapp 2009). It may also be worth noting that the original description of T. isthmiacum from Panama mentioned 5-articled palps, while many specimens (often regarded as belonging to the subspecies T. isthmiacum difficile Stock, 1966 ) are generally recorded with 6-articled palps in the Atlantic (e.g., Fage & Stock 1966; Stock 1966 a, 1979; Müller & Krapp 2009). This may be a whole distinct species, morphologically closer to T. boucheti (although different regarding the criteria mentioned above). It is therefore possible that T. boucheti has been identified as T. isthmiacum or T. isthmiacum difficile in the past.

Another similar species is Tanystylum hummelincki Stock, 1954 ( Fig. 5I–J ), with which the present material was mixed in Sabroux et al. (2019b). Indeed, the two species show similar appendages and lateral processes, and have bifid tubercles on the dorsal distal margin of the coxae. However, T. boucheti sp. nov. differs from T. hummelincki by the length of the proboscis, the height and shape of the ocular tubercle, and by the higher abdomen, which reaches beyond the ocular tubercle. The CO1 p-distances between the T. boucheti specimen and the material in this study identified as T. hummelincki range from 0.104 to 0.106 (see Appendix).

The species also strongly resembles Tanystylum evelinae Marcus, 1940 , described and only recorded from Saõ Paulo State, Brazil ( Marcus 1940). Tanystylum boucheti sp. nov. differs from T. evelinae by the presence of a posterior tubercle on the ocular tubercle, by the shape of the proboscis, which is conical rather than barrel-shaped, by the orientation of the abdomen, and by the size of the cement gland tube, which is longer in T. boucheti .

This species can be differentiated from other Tanystylum relatives using the following combination of characters: bifid tubercles on the anterodistal margin of coxae 1, the presence of one or two dorsal tubercles on the lateral processes, the conical shape of the proboscis, and the shape of the ocular tubercle.

A single specimen of the species was collected on the Atlantic coast of Martinique.

Distribution

Only known from the type locality.

Depth range

0– 2 m.

Figures

Fig. 5. Comparison between Tanystylum boucheti sp. nov. (A–H) and T. hummelincki Stock, 1954 (I– J). A–H. Holotype, ♂, MNHN-IU-2016-1074. I–J. ♂, MNHN-IU-2016-1063. A. Body, dorsal view. B. Body, lateral view (same scale as A). C. Palp. D. Third leg. E. Cement gland tube. F. Tarsus and propodus of third leg. G. Oviger. H. Oviger strigilis. I. Body, dorsal view. J. Body, lateral view. I and J same scale as A.