Ammothella dirbergi, 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 : 13-16

Ammothella dirbergi sp. nov.

urn:lsid:zoobank.org:act:7CCAA126-D880-4F80-B6D7-A7CB0C532E6C

Fig. 2

Amothella sp. 1 – Sabroux et al. 2019b (pro parte): 1522, 1525, 1531, tab. 1, figs 3, 5.

Material examined

Holotype MARTINIQUE • ♂; Pointe du Diamant; 14°27.5ʹ N, 61°02.9ʹ W; depth 3 m; 15 Sep. 2016; st. AB126; MNHN-IU-2016-833/ MK411148 .

Paratypes MARTINIQUE • 3 ♂♂; 2 ♀♀, 3 ♀♀ gr.; Case-Pilote ; 14°38.3ʹ N, 61°08.4ʹ W; depth 12 m; 8 Sep. 2016; st. AB159; MNHN-IU-2016-554 • 1 ♂, 3 ♀♀, 2 ♀♀ gr., 1 juv.; Presqu’Île de la Caravelle ; 14°48.4ʹ N, 60°52.8ʹ W; depth 23–25 m; 20 Sep. 2016; st. AB197; MNHN-IU-2016-577 • 1 ♂ ov., 1 juv.; same collection data as for preceding; MNHN-IU-2016-1252 • 3 ♀♀, 1 ♀ gr., 1 juv.; same collection data as for preceding; MNHN-IU-2016-1253 • 1 ♀ gr.; Fond Boucher ; 14°39.3ʹ N, 61°09.6ʹ W; depth 37–40 m; 1 Oct. 2016; st. AD283; MNHN-IU-2016-1054 • 1 juv.; same collection data as for preceding; MNHN- IU-2016-1224 • 2 ♂♂, 1 juv.; Baie de St-Pierre ; 14°45.1ʹ N, 61°11ʹ W; depth 17 m; 4 Oct. 2016; st. AB388; MNHN-IU-2016-1058 • 2 juvs; same collection data as for preceding; MNHN-IU-2016-1308 • 1 ♂; Ste-Marie ; 14°46.3ʹ N, 60°57.5ʹ W; depth 20 m; 20 Sep. 2016; st. AB260; MNHN-IU-2016-1066 • 1 ♀; Presqu’Île de la Caravelle ; 14°47.5ʹ N, 60°57.4ʹ W; depth 14 m; 4 Oct. 2016; st. AB562; MNHN- IU-2016-1091/ MK411047 • 1 ♀, 1 juv.; Baie du Robert ; 14°40.3ʹ N, 60°52.8ʹ W; depth 1–8 m; 25 Sep. 2016; st. AR455; MNHN-IU-2016-1095 • 1 ♀ gr., 1 juv.; same collection data as for preceding; MNHN- IU-2016-1275 • 2 ♀♀ gr., 1 juv.; Anse Couleuvre ; 14°50.4ʹ N, 61°13.4ʹ W; depth 7 m; 1 Oct. 2016; st. AB463; MNHN-IU-2016-1120 • 1 ♂ ov.; same collection data as for preceding; MNHN-IU-2016-1399 • 1 juv.; Baie de Fort-de-France ; 14°36.1ʹ N, 61°04ʹ W; depth 0–1 m; 29 Sep. 2016; st. AM034; MNHN-IU-2016-1153 • 2 ♂♂, 1 ♂ ov.; Rocher du Diamant ; 14°26.5ʹ N, 61°02.4ʹ W; depth 24 m; 14 Sep. 2016; st. AB173; MNHN-IU-2016-1158 • 1 ♀; Bellefontaine ; 14°39.7ʹ N, 61°09.6ʹ W; depth 9 m; 30 Sep.2016; st. AS 373; MNHN-IU-2016-1174/ MK411070 • 1 ♂; E of Le Robert ; 14°40.1ʹ N, 60°51.1ʹ W; depth 16 m; 18 Sep. 2016; st. AS 255; MNHN-IU-2016-1176 • 1 ♀; same collection data as for preceding; MNHN-IU-2016-1315 • 1 juv.; Baie de St-Pierre ; 14°44.5ʹ N, 61°10.8ʹ W; depth 44–47 m; 8 Oct. 2016; st. AS 572; MNHN-IU-2016-1208 • 1 ♀; Grande Anse du Diamant ; 14°27.9ʹ N, 61°01.4ʹ W; depth 17 m; 26 Sep. 2016; st. AB358; MNHN-IU-2016-1210 • 1 ♂; Rocher du Diamant ; 14°26.7ʹ N, 61°02.2ʹ W; depth 12 m; 21 Sep. 2016; st. AS 092; MNHN-IU-2016-1226 • 1 ♂; Grande Anse du Diamant ; 14°28ʹ N, 61°00.1ʹ W; depth 12 m; 26 Sep. 2016; st. AB360; MNHN-IU-2016-1238 • 1 ♀; same collection data as for preceding; MNHN-IU-2016-1239 • 1 ♂; Presqu’Île de la Caravelle ; 14°44.1ʹ N, 60°50.8ʹ W; depth 29 m; 18 Sep. 2016; st. AS 253; MNHN-IU-2016-1260/ MK411088 • 1 ♀ gr.; Le Robert ; 14°41ʹ N, 60°49.4ʹ W; depth 23 m; 24 Sep. 2016; st.AB401; MNHN-IU-2016-1266/ MK411092 • 1 juv.; Anse Noire ; 14°32ʹ N, 61°05.3ʹ W; depth 2–8 m; 6 Sep. 2016; st. AR100; MNHN-IU-2016-1286 • 1 ♂ ov.; Presqu’Île de la Caravelle ; 14°46.5ʹ N, 60°51.5ʹ W; depth 15 m; 22 Sep. 2016; st. AB350; MNHN-IU-2016-1303 • 1 ♀ gr.; Le Prêcheur ; 14°47.2ʹ N, 61°13.1ʹ W; depth 10–17 m; 3 Oct. 2016; st. AR383; MNHN-IU-2016-1306 .

Etymology

Latinized name, 2 nd decl. (masc.), genitive singular. This species is named after Guillaume Dirberg (MNHN), who collected many specimens of this species by sight, which is remarkable when considering the inconspicuousity of these animals.

Description (holotype, ♂, MNHN-IU-2016-833)

BODY. Trunk completely segmented, cuticle smooth. No dorsomedian ornamentation. Ocular tubercle long, about 5.5 times as long as base width, distal part broad and ovoid carrying pigmented eyes, pointy tip and 2 small pointy lateral sense organs (see Lehmann et al. 2017; Brenneis 2022). Lateral processes about twice as long as wide, well separated by about half of their own diameter, unornamented.

PROBOScIS. Pyriform, movable, longer than chelifore or trunk, with blunt tip.

ABDOMEN. Long, not extending beyond coxa 2, distal part inflated, then tapering at anus. Dorsally with club-shaped setae and simple setae medially and distally. Abdomen insertion articled on trunk.

CHELIFORE. 3-articled. Scape 2-articled, 1 st scape article about half as long as 2 nd. 2 nd article long, trumpet-shaped, carrying simple and club-shaped setae. Chela reduced as rounded buds, with distal seta on outer side.

PALP. 9-articled, carrying many setae mostly on last 5 articles. 1 st article shortest, 2 nd slightly shorter than 4 th. 3 rd article about as long as wide. 4 th article longest, about as long as 2 nd, about 6 times as long as wide, with scarce setae. 5 th article about 2.5 times as long as wide. 6 th article shorter than 5 th and twice as long as 8 th, about 4.5 times as long as wide. 7 th to 9 th articles shorter than 6 th, 9 th slightly longer.

OvIGER. 10-articled, with scarce setae. 1 st article as long as wide. 2 nd about 5 times as long as wide, 3 rd about 3 times as long as wide. 4 th article longest, slightly curved, about ⅙ longer than 2 nd. 5 th article slightly curved, about ⅔ of length of 4 th article. 7 th article longest within striglis, 10 th shortest. Strigilis spines compound, formula 3:2:1:2.

LEGS. Slender, carrying several short, simple and club-shaped setae, some of them in bouquet. Coxa 1 about 1.5 times as long as wide, with 2 dorsodistal club-shaped setae and often 2 tiny normal setae laterally. Coxa 2 subequal to coxae 1 and 3 together. Coxa 3 about twice as long as wide. Femur 6 times as long as wide; cement gland opening standing on distal margin on dorsal surface, as long tube about ⅓ of femur length. Tibia 1 longest. Tibia 2 slenderer, slightly shorter than tibia 1 but longer than femur. Tarsus short, trapezoid. Propodus about ⅓ as long as tibia 2, with 3 large basal spines, and smaller spines and setae on distal half of sole; main claw about half as long as propodus; auxiliary claws present, thinner, about same size as main claw.

MEASUREMENTS (mm). Trunk 0.54; abdomen 0.62; proboscis 0.70; chelifore 0.47; coxa 1 0.14; coxa 2 0.40; coxa 3 0.30; femur 0.84; tibia 1 1.03; tibia 2 0.92; tarsus 0.05; propodus 0.34; main claw 0.17.

Sexual dimorphism

Oviger articles more elongated in males, legs inflated in mature females.

Individual variability

Number of ovigeral spines variable, 1 to 4 on 1 st strigilis article, 1 or 2 on 2 nd strigilis article, 1 or 2 on 3 rd strigilis article. Lateral processes variable in length. Club-shaped setae sometimes slightly cleft, as on coxa 1 of left 2 nd leg of holotype.

Remarks

This species has a strong affinity with Ammothella indica Stock, 1954 , which is a common species in the Indo-Pacific, but never recorded in the Atlantic or Caribbean. The two species belong to the same group of Ammothella with club-shaped spines, and the lengths of the ocular tubercle, of leg and chelifore articles, and of the cement gland tube in males, are about the same. The relative lengths of palp articles are also similar between the two species. There are however some differences in the representations given by Stock (1954b) and Nakamura (1987). The three main morphological differences between A. indica and A. dirbergi sp. nov. are the following: (i) lateral sense organs are inconspicuous in A. indica ; (ii) the abdomen of A. dirbergi does not present a diadem of setae as in A. indica ; and (iii) the abdomen of A. dirbergi is not as curved as in A. indica .

This species can be differentiated from most other described species of Ammothella based on the long ocular tubercle and the club-shaped spines on the legs and abdomen. Species sharing these features are Ammothella fistella Lee & Arango, 2003 , A. gertrudae Müller & Krapp, 2009 , A. panamensis Child, 2004 , A. prolixa Child, 1990 and A. setacea ( Helfer, 1938) . Ammothella dirbergi sp. nov. differs from A. fistella in lacking tubular spines on the lateral processes and cephalon, and by its longer ocular tubercle and leg articles; it differs from A. gertrudae in lacking long tubercles on the lateral processes; it differs from A. panamensis in lacking club-shaped setae on the lateral processes, has longer tibiae 2, and has shorter lateral processes; it differs from A. prolixa in having a shorter distance between the lateral processes and no dorsal ornamentation of the lateral processes; and it differs from A. setacea in lacking long tubercles on the lateral processes and in having a shorter ocular tubercle and a completely segmented trunk ( Arnaud & Child 1988; Child 1990, 2004; Lee & Arango 2003; Müller & Krapp 2009).

Finally, Ammothella krappi sp. nov. is a close relative of A. dirbergi sp. nov. Ammothella dirbergi differs in having a shorter ocular tubercle (less than 6 times as long as wide in A. dibergi , more than 7 times in A. krappi ) and a shorter cement gland tube (⅓ as long as the femur in A. dirbergi , half as long in A. krappi ). The two species can be distinguished based on CO1 data (Sabroux et al. 2019): while in A. dirbergi intraspecific p-distances are between 0 and 0.012, the p-distances between the types of A. dirbergi and A. krappi are between 0.123 and 0.134, and those between A. dirbergi and A. aff. krappi are between 0.089 and 0.097.

Distribution

Only known from Martinique. Ammothella dirbergi was sampled on the Atlantic and Caribbean coasts.

Depth range

0.5– 47 m.

Figures

Fig. 2. Ammothella dirbergi sp. nov. A–F, I–L. Holotype, ♂, MNHN-IU-2016-83. G–H. Paratype, ♀, MNHN-IU-2016-1091. A. Body, dorsal view. B. Body, lateral view (same scale as A). C. Ocular tubercle, frontal view. D. Chelifore. E. Chela bud. F. Palp. G. Oviger. H. Oviger strigilis. I. Oviger. J. Oviger strigilis. K. Third leg. L. Tarsus and propodus of third leg.