Sarcotaces antimori, Piasecki & Boxshall, 2024

Piasecki, Wojciech & Boxshall, Geoffrey A., 2024, A new species of Sarcotaces (Copepoda: Cyclopoida: Philichthyidae) from Antimora rostrata (Actinopterygii: Gadiformes: Moridae), Acta Ichthyologica et Piscatoria 54, pp. 87-94 : 87

Sarcotaces antimori sp. nov.

Figs 1 , 2 , 3

Locality.

Goban Spur, northwestern Atlantic (49°49.9′N, 012°10.8′W)

Host fish.

blue antimora, Antimora rostrata ( Günther, 1878)

Infection site.

lateral musculature (flank)

Type material.

NHMUK 2022.198 holotype (male) and NHMUK 2022.199 allotype (female)

Description of female.

Body highly metamorphosed, semi-pyriform/semi-quadrangular with deep transverse furrows marking apparent segmentation, and without visible appendages. Surface of cephalosome and thoracic somites covered by papilliform protrusions. Deep transverse furrows without papilliform protrusions (Fig. 1A , 1B ). Abdominal somites without papilliform protrusions covering surface. Total length reaching 15.1 mm; total width 8.1 mm (Table 2 ). Body consisting of two parts equal in length. Anterior part semi-cylindrical, blunt, with frontal margin constituting straight line perpendicular to body axis; posterior part slightly wider, semi-conical (tapering posteriorly). Anterior part divided into 5 tightly packed (short) divisions covered with papilliform protrusions and separated by surface furrows. Apparent “segmentation” on dorsal surface not consistently matching furrows on ventral surface. Posterior part of body with two prominent, well-defined somites, diminishing in diameter, and conical abdominal part comprising three somites (abd II-abd IV) tapering stepwise towards conical tip. Surface of posterior part with few papilliform protrusions on dorsal side (Figs 1B , 2A ). Oral lobe located anteriorly on ventral surface, doughnut-shaped, densely covered with papillae around perimeter. Two larger processes present on body surface immediately posterior to oral lobe (Figs 1A , 2B ).

Description of male.

Body (Fig. 3A ) markedly smaller than that of female, and substantially different in structure; strongly elongate, subcylindrical, unsegmented, with smooth surface. Body consisting of two parts: anterior cephalothorax (20% of body length) and posterior “trunk” (80%). Semi-triangular cephalothorax with three very pronounced lateral indentations marking traces of body segmentation and defining cephalosome from first and second pedigerous somites, the latter bearing prominent posterolateral lobes. Cephalosome with rounded frontal margin produced anteromedially, lateral margins slightly convex; bearing four pairs of appendages. Post-cephalothoracic “trunk” cylindrical and legless, elongate with discrete traces of segmentation; becoming distinctly wider posteriorly and with prominent caudal rami on posterolateral corners. Total body length of male 2.07 mm, excluding caudal rami, and 2.90 mm with symmetrical caudal rami; caudal ramus length 0.83 mm (Table 2 ). Maximum cephalothorax width 0.61 mm. Trunk width ranging from 0.21 to 0.54 mm. Caudal rami constituting 28.6% of total length and 40.1% of body length. Cephalothoracic appendages well developed and consisting of antennulae, antennae, mandibles, maxillae, and 2 pairs of legs. Antennule (Fig. 3B ) four-segmented with segments diminishing in length and diameter towards tip: first segment longest lacking setation; second segment slightly shorter with single seta posteriorly; third segment slightly longer than wide with one seta anteriorly and one long seta posteriorly; fourth segment short with three long setae posteriorly and three long setae terminally. Antenna (Fig. 3C ) indistinctly three-segmented comprising coxobasis plus two-segmented endopod; endopodal segments each bearing single large terminal claw. Mandible (Fig. 3D ) large, subchelate, wide at base; tapering towards powerful distal claw. Maxillulae not observed. Maxillae (Fig. 3E ) small, uniramous, with triangular base bearing conical terminal segment armed with small seta at base. Maxillipeds absent. First legs (Fig. 3F ) biramous with semi-quadrangular two-segmented protopod: exopod one-segmented and armed with four stout claws; endopod one-segmented with two stout claws. Elaborate, Y-shaped interpodal sclerite present on ventral body surface between first thoracopods. Second legs (Fig. 3G ) similar to first: exopod with three stout claws (with single seta at base laterally); endopod with three stout claws. Interpodal sclerite almost completely reduced. Caudal rami very long, thick powerful gently tapering towards distal tip (Fig. 3A ), armed with single minute setule near base.

Remarks.

The female of Sarcotaces antimori sp. nov. differs from that of all known species by possessing very dense coverage over the surface of the cephalosome and thoracic somites with relatively large papilliform protrusions. Another distinct feature of this species is that the surface of the oral lobe is regularly and densely covered with large papilliform protrusions, similar to those covering the rest of the body. This feature distinguishes Sarcotaces antimori sp. nov. from its congeners

The male of Sarcotaces antimori sp. nov. differs from that of all known species by the deep indentations in the lateral margins of the cephalothorax. Another distinct character is the shape of the trunk which widens substantially posteriorly. In addition, the antennule has a unique setal formula (0, 1, 2, 6) and the first legs lack the outer protopodal seta at the base of the exopod (Table 2 ).

Etymology.

The specific name Sarcotaces antimori is an adjective derived from the name of the host genus.

Figures

Figure 1. Female of Sarcotaces antimori sp. nov. (allotype) from blue antimora, Antimora rostrata. (A) ventrolateral view; (B) dorsolateral view. OL = oral lobe. Scale: 10 mm. Photo: Harry Taylor (NHM Photo Studio, London, UK).

Figure 2. Female of Sarcotaces antimori sp. nov. (allotype) from blue antimora, Antimora rostrata. (A) posterior part; dorsal view; (B) Anterior part; vental view. Scale bars: 5 mm. Photo: Dr Brygida Wawrzyniak-Wydrowska (University of Szczecin, Poland).

Figure 3. Male of Sarcotaces antimori sp. nov. (holotype) from blue antimora, Antimora rostrata. Habitus (A); antennule (B); antenna (C); mandibles (D); maxillae (E); first legs (F); second legs (G). All images in ventral view. Scale bars: 0.2 mm (A), 0.05 mm (D, E, F, G), 0.02 mm (B), 0.01 mm (C).