Clavellotis dubius Castro Romero, Montes, Ӧtkener & Campos, 2025

Romero, Raul Castro, Montes, Martin M., Ӧtkener, Ahmet, Shimabukuro, Marina Ibañez, Theiller, Mariela & Campos, Leonardo, 2025, Two new species of Clavellotis (Copepoda: Lernaeopodidae) with an approach to the phylogeny of the genus and its relationships inside the Clavella-Branch, Zootaxa 5679 (2), pp. 217-242 : 221-225

Clavellotis dubius Castro Romero, Montes, Ӧtkener & Campos sp. nov.

Figs. 1–4

Host: Chromis crusma (Valenciennes, 1833)

Site of infection: gills arcs

Type Locality: Antofagasta, Chile South Pacific . 23°38'39 S; 70°24'39 W

Prevalence and mean intensity: 10.24% (13/128); 1.0

Type Material: deposited in the Natural History Museum , Santiago Chile, Holotype female MNHNCL No Cop- 15160, Paratypes females: MNHNCL Cop: 15161, Cop-15162, Allotype MNHNCL Cop15163 .

Etymology: the specific name dubius refers to the doubts that arose by the identity of specimens of Clavellotis confused with some Clavella species.

Description of females: Measurements based on 3 female specimens in micrometers. Cephalothorax elongate ( Fig. 1A), oblong, with basal process (length 2,197 [1,974 –2,308], width 308 [282–333]). Trunk (length 1,650 [1,308 –1,846], width 829 [744–974]), perpendicular to cephalothorax ( Fig. 1A). Trunk oblong, short genital process (length 256 [266–256], width 154 [103–205]). Egg sacs: length 1,731 (1,410 –2,051), width 475 (436–513). Maxilla ( Fig. 1B) median size (length 940 [897–974], width 221 [120–280]), rami separated. Bulla short, cup shaped. Excretory duct short, at maxilla base. Antennule ( Fig. 1C) 4-segmented. Basal segment wide. The second segment with whip. Distal segment armed with: elements 1, 3; digitiform seta 4; bifid seta 5; seta 6. Elements 1, 3 wide at base, tapering distally, like tubercles. Antenna ( Fig. 1D) biramous. Sympod as long as exopod. Exopod globose, longer than endopod, with 5 tiny spinules on dorsal margin. Endopod bi-segmented, with strong spiniform process (1), setae 2, 3, and ventral pad of 3 spinules. Labrum ( Fig. 1E) subtriangular, with 9 apical setae. Maxillule ( Fig. 2A) bilobate. Endite: 2 papillae, each with long seta of equal length, plus short dorsal seta. Palp short, lateral, with papilla bearing 2 setae. No additional armature. Mandible ( Fig. 2B) dental formula: P1, P1S1, P1S1, B5 (3 well-developed, 2 short basal teeth). Maxilliped ( Fig. 2C) corpus strong, with a single spine in myxal area. Shaft with a short spine on basal third laterally. Claw slightly curved ( Fig. 2D), ventral barb extending beyond half-claw length. Base near barb with: 3 short spines. No additional armature.

Description of male: Clavellotis -like ( Fig. 3A). Body short, subcircular. Genital process lobe-shaped, below maxilliped. Antennule ( Fig. 3B) uniramous, 3-segmented. The second segment is the longest. No whip or solus. Apical armature:elements 1, 2, 3; seta 4, 6; 5(bifid seta). Antenna ( Fig. 3C) biramous. Endopod longer than exopod. Endopod bi-segmented, distal segment with strong curved process; ventral surface with medial spiniform process, rows of spinules. Exopod globose, lacking armature.

Labrum ( Fig. 3D) subtriangular, with rostral seta + 8 surrounding setae. Mandible not detected. Maxillule ( Fig. 3E) bilobated. Endite: 2 papillae, each with 1 seta of equal size and 1 small dorsal seta. Palp: short ventral lobe, 2 unequally long setae.

Maxilla ( Fig. 4A) with strong base, rounded inner margin, distal flange receiving slightly curved claw. Maxilliped ( Fig. 4B, C) basal segment rectangular, with pectinate plate (4 teeth) on distal outer margin. Distal segment operculum-like, short inner margin process.

Remarks

The type species of the genus, C. dilatata , is characterized by an aliform process at the base of the cephalothorax, clearly separated from it, and by a short, nipple-like structure (excretory duct) at the base of the maxilla. These features confer a distinctive shape to this region. The present specimens cannot be considered conspecific with those species that have a subcircular trunk and a short maxilla, such as C. briani , C. branchiostegui , C. dilatata , and C. tarakihi Additionally , C. bilobata must also be excluded, as it possesses a bilobed subcircular trunk. The species that should be compared with the present specimens are C. characis , C. fallax , C. pagri , C. sargi , C. strumosa , and C. sebastidis .

In C. characis , the aliform process is suborbicular, whereas in C. dubius sp. nov., it is elongated. The exopod of the antenna in C. characis is densely spinulated along the dorsal margin, with three additional spinules on the lateral surface, while in C. dubius sp. nov., there are at least five spinules.

Clavellotis fallax differs from the present specimens by having a more elongated maxilla, whereas in C. dubius sp. nov., it is shorter. Additionally, the aliform process in C. fallax is globose and blunt, whereas in C. dubius sp. nov., it is distally narrower. The maxillule in C. fallax has a palp with two setae of different lengths, whereas in the present specimens, these setae are of approximately equal size. Furthermore, the maxilliped in C. fallax has a row of denticles on the ventral margin of the claw, whereas in C. dubius sp. nov., there are only three denticles.

In C. pagri , the genital process is very reduced and narrow, while in C. dubius sp. nov., it is slightly longer and wider. The aliform process in C. dubius sp. nov. is elongated, whereas in C. pagri , it is globose. The maxilla in C. pagri is short, whereas in C. dubius sp. nov., it is long. The exopod of the antenna in C. pagri is longer than the endopod and densely spinulated, whereas in C. dubius sp. nov., it is slightly longer but has fewer spinules. Additionally, in C. pagri , the maxillule has a palp with two setae of unequal length and a densely spinulated base, whereas in C. dubius sp. nov., the setae are of equal length and lack additional armature.

The present specimens differ from C. sargi in that the antennules have elements 1 and 3 well developed and subtriangular, whereas in C. sargi , these elements are reduced (element 1) or absent (element 3). The maxillule palp in C. sargi has setae of different lengths, whereas in the present specimens, the setae are of equal length. Additionally, C. sargi has a well-developed genital process, whereas in the present specimens, it is short.

Clavellotis strumosa shares the general trunk shape with C. dubius sp. nov., but they differ in the aliform projection, which in C. strumosa has a distal constriction, giving the appearance of an annexed suborbicular structure. This type of projection is also found in C. briani , but not in the present specimens. Additionally, C. strumosa has a densely spinulated pad on the exopod of the antenna, whereas in the present specimens, there are only five spinules.

The most notable difference with C. sebastidis is the maxilla, which is long in C. sebastidis , whereas in C. dubius sp. nov., it is of medium size. The aliform process in C. sebastidis is suborbicular, whereas in C. dubius sp. nov., it is elongated. The exopod of the antenna in C. sebastidis is densely spinulated along the dorsal margin, whereas in C. dubius sp. nov., it has only five spinules. Additionally, C. sebastidis has a maxillule palp with two setae of unequal length, whereas in C. dubius sp. nov., the setae are of equal length. The maxilliped of C. sebastidis has a row of spinules on the ventral margin of the shaft, whereas in C. dubius sp. nov., there are only three spinules located on the distal lateral margin near the base of the annexed barb. These morphological differences support the conclusion that the present specimens represent a new species, described herein.