Collettea gaditana, Esquete & Cunha, 2018

Esquete, Patricia & Cunha, Marina R., 2018, Additions to the Tanaidomorpha (Crustacea: Tanaidacea) from mud volcanoes and coral mounds of the Gulf of Cadiz and Horseshoe Continental Rise, Zootaxa 4377 (4), pp. 517-541 : 526-530

Collettea gaditana sp. nov.

( Figs 6–7 )

Material examined. Holotype—♀(MNCN 20.04/11446), cruise TTR15, station TTR15_AT575, USNEL boxcore, 26.07.2005, GoC, Mercator MV, 35°17.903'N, 06°38.715'W, 355 m depth, crater of MV, mud breccia; near seep, coll. MRC.

Further paratypes: Gulf of Cadiz—Mud volcanoes. Mercator MV: station MSM01-3 _237.2, multicore, 0 6.05.2006, 35°17.914'N, 06°38.687'W, 353 m, crater of MV; mud breccia, near seep, one ♀ ( DBUA00002218.01 ), coll . MRC; station 64PE253_49, NIOZ boxcore, 14.10.2006, 35°17.90'N, 6°38.64'W, 360 m, crater of MV, clayeysilty sand with carbonate debris, H2S smell, one ♀ (DBUA00002219.01), coll. Clara F. Rodrigues (CFR); Gemini MV: station 64PE253_13, NIOZ boxcore, 0 8.10.2006, 35°16.65'N, 6°46.11'W, 516 m, flank of MV; silty clay, one specimen (DBUAXXXX). Coll. CFR

Gulf of Cadiz—Carbonate and coral mounds. Pen Duick Escarpment: station 64PE253_39, NIOZ boxcore, 13.10.2006, 35°18.90'N, 6°47.90'W, 560 m, sandy silty clay, one ♀ ( DBUA00002219.03 Mound B: station 64PE268_13A, NIOZ boxcore, 0 3.05.2007, 35°17.997'N, 6°44.488'W, 475 m, sandy silty clay with coral fragments, one neuter ( DBUA00002220.01 ). All coll. CFR .

Additional comparative material examined. - Collettea cylindrata (Sars, 1882) : six specimens (syntypes), NHMUO F10159; one specimen, NHMUO F10159.

Etymology. “Gaditana” is the demonym (feminine) of the inhabitants of Cádiz, the city which the Gulf of Cadiz is named after.

Diagnosis. Body 8.6 times as long as broad. Pereon distinctively longer than pleon. Pleon distinctively longer than pleotelson. Antennule with distinct cap-like terminal segment. Antenna article 4 with fusion line. Maxilliped endite with paired tubercles and no seta. Uropods short, not reaching pleotelson distal border.

Description of female DBUA00002218.01. Body ( Fig. 6A, B ) slender, 8.6 times longer than broad, length 2.3 mm. Cephalothorax 0.2 times as long as body, 1.5 times as long as broad, as long as pereonites 1–2 and half of 3 together. Pereonite 1 0.4 times as long as broad. Pereonite 2 1.6 times as long as pereonite 1, 0.7 times as long as broad. Pereonite 3 about as long as pereonite 2. Pereonites 4–5 about as long as broad. Pereonite 6 0.8 times as long as pereonites 4 and 5. Pleon as broad as pereon, 0.2 times as long as body, about as long as pereonites 4–6 together; all pleonites alike. Pleotelson 1.5 times as long as broad, as long as pleonites 3–5 and half of 2 together.

Antennule ( Fig. 6C ) article 1 3.2 times as long as broad, with one outer subdistal seta. Article 2 1.2 times as long as broad, with one inner distal simple seta and tuft of three outer distal penicillate setae. Article 3 as long as broad, with one outer subdistal simple seta and one inner distal short seta. Article 4 3.0 times as long as broad, naked. Article 5 cap-like, with three simple setae and one aesthetasc. Antenna ( Fig. 6D ) article 1 1.2 times as long as broad, with one dorsodistal seta. Article 2 0.7 times as long as broad, with one dorsodistal seta. Article 4 with faint division line, five times as long as broad, naked. Article 5 2.5 times as long as broad, naked. Article 6 with five distal setae.

Mouthparts. Labrum semicircular (not figured). Left mandible ( Fig. 6E ) pars incisiva process with two larger and three smaller cusps, lacinia mobilis with five cusps; pars molaris armed with teeth. Right mandible ( Fig. 6F ) as left but without lacinia mobilis. Labium ( Fig. 6G ) consisting of one pair of naked lobes. Maxillule ( Fig. 6H ) endite with eight distal spines, three of them distally bilobed; palp with two setae (not figured). Maxilla not recovered.

Maxilliped ( Fig. 6I ) endite with two tubercles. Palp article 1 naked, article 2 and 3 with three inner setae, article 4 with four distal and one subdistal setae.

Cheliped ( Fig. 7A ) attached via elongate sclerite. Basis 1.8 times as long as broad. Merus with ventral seta. Carpus 1.7 times as long as broad, with one ventral seta. Propodus 2.0 times as long as broad, with inner row of three spines, the ventral-most the longest; chela fixed finger with two ventral setae and three setae near cutting edge; cutting edge distal half crenulated with one subdistal denticle. Dactylus as long as fixed finger, with one inner medial seta.

Pereopod 1 ( Fig. 7B ) coxa with one seta. Basis slightly curved, four times as long as broad. Ischium with ventral seta. Merus 0.3 times as long as basis, with one ventrodistal seta. Carpus 1.7 times as long as merus, 2.8 times as long as broad, with one dorsodistal seta reaching half length of propodus and one ventrodistal, shorter seta. Propodus about as long as carpus, with subdistal spine. Dactylus and unguis together 1.1 times as long as propodus, unguis 1.6 times as long as dactylus.

Pereopods 2–3 ( Fig. 7C, D ) coxa with seta. Basis straight, 5.0 times as long as broad. Ischium with ventral seta. Merus 0.3 times as long as basis, with one ventrodistal seta. Carpus 1.6 times as long as merus, with two short and one long setae. Propodus 1.3 times as long as carpus, with ventrodistal spine. Dactylus and unguis together 1.1 times as long as propodus, unguis 1.6 times as long as dactylus.

Pereopods 4–6 ( Fig. 7E ) coxa with seta. Basis 3.7 times as long as broad, visibly broader distally. Ischium naked. Merus with pair of ventrodistal spines. Carpus 1.7 times as long as broad, with pair of ventrodistal serrulate spines, one simple dorsodistal spine and one simple dorsodistal seta. Propodus 4.8 times as long as broad, with dorsodistal spiniform apophysis, one dorsodistal serrulate spine and pair of ventrodistal serrulate spines. Dactylus and unguis together 1.3 times as long as propodus, unguis 0.9 times as long as dactylus.

Uropod ( Fig. 7F ) protopod 0.7 times as long as broad, naked. Endopod first segment about as long as basis, naked; second segment 0.6 times as long as first, with one subdistal and three long distal setae. Exopod with one long simple seta.

Remarks. Two species are described from localities near the GoC: Collettea rotundicauda Kudinova- Pasternak, 1986, from waters off Portugal, can be readily distinguished from C. gaditana sp. nov. in having a pleon distinctly shorter than pleotelson, uropods long, inner rami about twice as long as basis, and pereopods with setules on propodus and dactylus; C. vermiformis (Lang, 1971) from the Alboran Sea, has a pleon longer than pereon, antenna without dorsal setae on articles 2 and 3, pereopods 1 to 3 dactylus with proximal seta, carpus without dorsodistal seta, pereopods 4 to 6 with four serrulate spines, and uropods proportionally longer, with protopod distinctively longer than wide.

Collettea cylindrata (Sars, 1882) recorded along the coast of Norway and Davis Strait (Hansen 1913; Lang 1971; Larsen 2000; Sars 1882, 1896) is a species with high intraspecific variation, and some of the morphologies described by the various authors also show similarities with C. gaditana . For instance, Sars (1882, 1896) described two different morphologies of the habitus of C. cylindrata , one corresponding to the females and the other corresponding to immature males, and Hansen (1913) and Lang (1971) provided further descriptions and illustrations of additional intraspecific variation on antennule and chela. The habitus of the female specimens illustrated by Sars (1896, pl. XVI Fig. 1 ) and redescribed by Lang (1971) have the same proportions of carapace, pereonites, pleonites and pleotelson as C. gaditana . Likewise, characters of the chela such as propodus dimensions and number of setae in the setal row lie within the variability described by Lang (1971, Fig. 1 ). Nevertheless, C. cylindrata differs from C. gaditana in having a pair of setae on the carapace, the maxilliped endite with a seta and no cusps, pereopods 1 to 3 dactylus with a proximal seta and the carpus without dorsodistal seta, and pereopods 4 to 6 with four serrulate spines instead of three.

Distribution and ecology. This species was found in mud breccia near active seeps but mostly in very fine sediments (clay) with carbonate and fossil coral debris collected from mounds and inactive sites of mud volcanoes (Mercator and Gemini) in the Moroccan margin between 241–575 m depth.

Figures

FIGURE 1. MAP OF The GULF OF CADIZ AND HORSeShOe AbYSSAL PLAIN ShOWING The STRUcTUReS MeNTIONeD IN ThIS STUDY.TRIANGLeS: MUD VOLcANOeS.CIRcLeS:CARbONATe MOUNDS.

FIGURE 6. Collettea gaditana sp. nov. FeMALe hOLOTYPe MNCN 20.04/11446: A, hAbITUS (DORSAL VIeW). B, hAbITUS (LATeRAL VIeW). FeMALe SPecIMeN DBUA00002218.01: C, ANTeNNULe; D, ANTeNNA; E, LeFT MANDIbLe; F, RIGhT MANDIbLe; G, LAbIUM; H, MAXILLULe;I, MAXILLIPeD.

FIGURE 7. Collettea gaditana sp. nov. FeMALe SPecIMeN DBUA00002218.01: A, cheLIPeD;B, PeReOPOD 1; C, PeReOPOD 2; D, PeReOPOD 3; E, PeReOPOD 4; F, UROPOD.