Teratonotum, Sabroux & Corbari & Krapp & Bonillo & Prieur & Umr & Cnrs, 2017

Sabroux, Romain, Corbari, Laure, Krapp, Franz, Bonillo, Céline, Prieur, Stépahnie Le & Hassanin, Alexandre, 2017, Biodiversity and phylogeny of Ammotheidae (Arthropoda: Pycnogonida), European Journal of Taxonomy 286 (286), pp. 1-33 : 16-18

Teratonotum gen. nov.

urn:lsid:zoobank.org:act:CD6D82C7-E0EC-4E46-A2C6-559678E48B29

Fig. 6

Type species

Ammothella stauromata Child, 1982: 270 (in list), 271–273, fig. 1.

Ammothella stauromata – Arango 2003a: 2730–2731 . — Bamber 2004: 2–3 , 21 (in tab.); 2007a: 256 (in list). — Child 1987: 180 (in list); 1988: III (in list), 5–7, 30–31 (in list); 1990: 316 (in description); 1996: 544; 1998: 290 –291. — Müller 1989: 125; 1990a: 66; 1990b: 106. — Nakamura & Child 1988: 809–810. — Stock 1994: 29.

Diagnosis

Trunk slender, totally segmented; ocular tubercle present, with three long, slender dorso-median tubercles; abdomen long, straight, almost vertical; scapes bi-articled, more proximal article with dorsodistal slender tubercle, chelae atrophied in adult; palps 9-articulated, originating from bulbous tubercles (with slender tubercle) placed anterolaterally on cephalic segment; oviger 10-articulated, originating ventral to first lateral processes, strigilis with denticulate spines; third leg with a single cement tube at anterior tip in males, tarsus short, propodus curved, auxiliary claws present.

Etymology

τέρας (téras): monster, and νῶτον (nōton): back (ancient Greek); referring to its remarkable back tubercles. Gender neutral.

An underestimated biodiversity

The CO1 data generated in this study on specimens collected during the recent MNHN expeditions indicate that the diversity of Ammotheidae was poorly represented in the nucleotide databases, such as GenBank and BOLD ( Ratnasingham & Hebert 2007). Indeed, all our new CO1 sequences show at least 7% of nucleotide divergence with the ca 430 pycnogonid sequences available in GenBank, and even up to 11% if the genus Sericosura is excluded from the comparisons. This means that none of the ammotheids analysed here can be identified at the species level using molecular barcoding. Actually, this result is not surprising if we consider that most of the pycnogonids previously registered in the GenBank and BOLD databases were collected along the coastlines of temperate South America ( Chile and Argentina) and Antarctica ( Fig. 1 ), whereas our specimens come from widely spread geographic areas, i.e., French Guiana, Guadeloupe, Madagascar, Marquesas Islands, New Caledonia, Papua New Guinea, Vanuatu, and Atlantic and Pacific vents ( Fig. 2 ). Besides, another issue for molecular taxonomy is the fact that most of the barcode sequences deposited in BOLD were not identified to the family level (958 of 1315, 72.85%). Beyond a problem of molecular taxonomy, ammotheids, and more generally pycnogonids, suffer from a lack of knowledge. For instance, our specimens collected along the coastlines of southern Madagascar show a far more rich diversity than previously recorded in the literature: five different species of Achelia were identified, whereas only two species were previously known from Madagascar; none of the species of Ammothella and Endeis studied here were known in the region; and a new species of Acheliana was found ( Arnaud 1971a, 1971b, 1972, 1973; Stock 1974). In a more general way, it seems that the large collection of sea spiders assembled during the MNHN expeditions represents an important input to our knowledge of this group and promises the description of numerous new species (in prep.).

Figures

Fig. 6. Teratonotum stauromatum (Child, 1982) gen. et comb. nov. (MNHN-IU-2013-17964). A. Dorsal view. B. Propodus of third leg. C. Dorsal view of body. D. Ventral view of body. Abbreviations: ab = abdomen; ac = auxiliary claw; ch = chelifore; ct = chelifore tubercle on the anterior tip of the first scape; dt = dorsal tubercle; mc = main claw; ot = ocular tubercle; ov = oviger; pa = palp; pb = bulbous tubercle bearing the palp;pp = propodus; pr = proboscis; s =strigilis; t = tarsus.Scale bars:A = 0.5 mm; B = 0.1 mm; C–D = 0.2 mm.

Fig. 1. Barcode richness in GenBank before and after this study. A–B. Number of CO1 haplotypes before (A) and after (B) this study as a function of the origins of the specimens sequenced. C. Number of species (grey) and genera (black) represented by a CO1 sequence found in GenBank databases before (left) and after (right) this study, classified by ecoregions. Littoral ecoregions defined according to Spalding et al. (2007) and abyssal ecoregions following a simplification of Bachraty et al. (2009).

Fig. 2. Regional distribution of the studied specimens. Green diamonds indicate locations where specimens were collected at shallow depths (<100 m), blue circles those from deep-sea samplings; the combinations of both symbols indicates mixed samplings (below and above 100 m depth). 1: Futuna; 2: Marquesas Islands; 3: Guadeloupe; 4: French Guiana; 5: Mid-Atlantic Ridge, Snake Pit site; 6: Mid- Atlantic Ridge, Logatchev site; 7: Mid-Atlantic Ridge, Lucky Strike site; 8: Mozambique Channel; 9: South Madagascar; 10: Antarctica, Terre Adélie; 11: Papua New Guinea; 12: New Caledonia and Vanuatu.