Tanystylum ingrallis, 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 : 30-33

Tanystylum ingrallis sp. nov.

urn:lsid:zoobank.org:act:2CBAF7F7-5414-4617-80C9-809155ADA7FE

Fig. 6

Tanystylum sp. 3 – Sabroux et al. 2019b: tab. 1, fig. 3.

Material examined

Holotype MARTINIQUE • ♂; Fond Boucher ; 14°39.3ʹ N, 61°09.6ʹ W; depth 37–40 m; 1 Oct. 2016; st. AD283; MNHN-IU-2016-1055/ MK411038 .

Paratype MARTINIQUE • 1 ♂; Macouba ; 14°55.1ʹ N, 61°09ʹ W; depth 80 m; 24 Sep. 2016; st. AD261; MNHN- IU-2016-867/ MK411178 .

Etymology

Contraction of ‘ in grallis ’, in + plural accusative of the Latin gralla, - ae (1 st decl, fem.): ‘on stilts’, referring to the long legs of this species, relatively to most instars of the genus.

Description (holotype, ♂, MNHN-IU-2016-1055)

BODY. Trunk completely unsegmented, discoidal; cuticle granular. No dorsomedian ornamentation. Ocular tubercle cylindrical, higher than abdomen, about 4/3 as tall as wide, carrying four large pigmented eyes, one acute terminal spur anteriorly and 2 small lateral sense organs. Cephalon with 2 small lateral tubercles at anterior margin. 1 st lateral processes about 4/3 as long as wide, other lateral processes about as long as wide; all lateral processes jointed; 1 st lateral process without ornamentation, 2 nd, 3 rd and 4 th lateral processes with one anterior tubercle on distal margin, carrying one seta.

PROBOScIS. Proximal half broad and rounded, distal half tubular, blunt at tip, bent ventrally, about as long as distance between cephalon distal margin and abdomen base.

ABDOMEN. Long, diagonally oriented, inflated distally, with light inflation at base.Anus reaching beyond first coxae of 4 th legs. Abdomen carrying setae, mostly on distal inflated part. No basal segmentation. One dorsal tubercle in distal part, carrying setae.

CHELIFORE. 1-articled, composed of one small knob with one distal spine.

PALP. 6-articled, with setae mostly on last 2 distal articles. 1 st article shortest, wider than length. 2 nd article about 2.5 times as long as wide. 3 rd article as long as 1 st article. 4 th article longest, about 1.7 times as long as 2 nd article, about 3.5 times as long as wide, with cannula (gland?) on outer side. 5 th article about 0.2 times as long as wide. 6 th article about 3.5 times as long as wide.

OvIGER. 10-articled, with scarce setae. 1 st article as long as wide. 2 nd article more than 1.5 times as long as wide. 3 rd article about twice as long as wide. 4 th and 5 th articles subequal and longest, 4 th about 3.5 times as long as wide, 5 th about 4 times as long as wide. 6 th article about twice as long as wide. 7 th article about as long as wide, presenting one distal low spur carrying long setae. 8 th article about as long as wide. 9 th article about twice as long as wide. 10 th article about 1.5 times as long as wide. Strigilis spines simple, strigilis formula 2:1:1:2.

LEGS. Rather long for the genus, 1 st leg pair longer than others. Coxa 1 shorter than wide, with 4 tubercles mounted with seta on distal margin of 1 st and 2 nd legs: one dorsomedian, two dorsolateral and one ventrolateral on posterior side; or with 3 tubercles on 3 rd and 4 th legs: one dorsomedian, one dorsolateral and one ventrolateral on posterior side. Coxa 2 longer than coxa 1 or 3, with one large distal tubercle on anterior side and 2 or 3 distal tubercles on posterior side, all mounted with one seta at tip. Coxa 3 as long as broad, with ventral setae. Femur straight, with long dorsal spur at distal margin with one lateral cement gland tube on inner side, rounded at base and tubular distally. Tibia 1 shorter than femur, with two low dorsal knobs mounted by long setae and distal dorsomedian spur. Tibia 2 longer than tibia 1 or femur, with scarce setae, and 3 low knobs on dorsal surface mounted with long setae. Tarsus trapezoid, short, about as long as wide, carrying one large spine and setae on ventral surface. Propodus gently curved, with low heel carrying 2 large heel spines, plus one smaller spine more distally. Main claw curved, about half as long as propodus. Auxiliary claws present, about 0.6 times as long as main claw.

MEASUREMENTS (mm). Trunk 0.84; abdomen 0.55; proboscis 0.80; coxa 1 0.22 (1 st leg), 0.24 (2 nd leg); coxa 2 0.46 (1 st leg), 0.36 (2 nd leg); coxa 3 0.27 (1 st leg), 0.28 (2 nd leg); femur 1.25 (1 st leg), 0.82 (2 nd leg); tibia 1 1.17 (1 st leg), 0.78 (2 nd leg); tibia 2 1.40 (1 st leg), 1.04 (2 nd leg); tarsus 0.10; propodus 0.50; main claw 0.28.

Sexual dimorphism

No female currently available.

Individual variability

On the other available specimen, the chelifores are almost not visible in dorsal view.

Remarks

Tanystylum ingrallis sp. nov. is readily discriminated from most other described species by the peculiarly long and slender legs and the absence of nodules on legs. Most species of Tanystylym have their propodus conspicuously longer than half the tibia 2, while here the propodus is just half as long as tibia 2 for the second, third and fourth legs, and much smaller for first legs. Only T. lamonti Staples, 2019 , T. tiara Staples, 2019 , T. zuydtorpi Arango, 2009 and T. paramexicanum Müller & Krapp, 2009 have long legs as well. Tanystylum lamonti , T. tiara and T. zuydtorpi are much different from T. ingrallis , due for example to the shape of their proboscis (long and barrel shape in the two former species, pyriform in the latter), and their longer chelifores. On the other hand, T. paramexicanum shares some morphological characters with this new species: the shape of the proboscis, the strong spur on the anterior margin of the ocular tubercle and the presence of 3 or 4 tubercles on coxae 1. However, the two species do not only differ by the absence of tubercles on the lateral processes, the much lower tubercles on coxae 1, the shorter size of coxae 2 and the bent ocular tubercle tip in T. paramexicanum , but also by the longer abdomen, the presence of tubercles on coxae 2 and the presence of a high tubercle on the distal margin of tibia 1 in T. ingrallis . Also, there is no specific mention of a longer first pair of legs in T. paramexicanum . Regrettably, only females are known for T. paramexicanum , so it is not possible to compare the cement gland opening of the two species. Indeed, the lateral opening of the cement gland tube in T. ingrallis is another strong diagnostic character.

The morphologically closest species to T. ingrallis sp. nov. is probably T. duospinum Hilton, 1939 , which presents a similar proboscis, and has the same palp structure. These two species are, however, differentiated by several conspicuous characters: (i) the abdomen of T. ingrallis extends beyond the first coxae of the fourth leg, while it does not reach the distal margin of the lateral processes in T. duospinum ; (ii) in T. ingrallis , the abdomen is oriented diagonally, while it is almost vertical in T. duospinum ; (iii) the anterior tubercle-ornamented coxa 1 is bifurcated in T. duospinum on the first leg ( Müller & Krapp 2009), but not in T. ingrallis ; (iv) the dorsodistal spur of the legs is longer in T. ingrallis compared to T. duospinum ; (v) knobs dorsally positioned along the legs are smaller and more spaced in T. ingrallis compared to T. duospinum ; (vi) tibia 2 is longer relative to tibia 1 in T. ingrallis compared to T. duospinum . Two specimens of the species were collected on the Caribbean and northern coasts of Martinique.

Distribution

Only known from Martinique.

Depth range

40– 80 m.

Figures

Fig. 6. Tanystylum ingrallis sp. nov., holotype, ♂, MNHN-IU-2016-1055. A. Body, dorsal view. B. Body, lateral view (same scale as A). C. Palp. D. Oviger. E. Oviger strigilis. F. Second leg. G. Tarsus and propodus of second leg. H. Femur of third leg, dorsal view (same scale as F). I. Close-up of distal spur on femur of second leg, and cement gland tube. J. First leg (same scale as F).