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

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

Figs. 5–7 View FIGURE 5 View FIGURE 6 View FIGURE 7

Host: Girella laevifrons (Tschudi)

Site of infection: branchial arches,

Type Locality: Antofagasta ( Chile), 23°38'39 S and 70°24'39 W GoogleMaps

Prevalence and Mean intensity 19.4% (7/36), 1.0

Type material deposited in the Natural History Museum MNHN, Santiago Chile, Holotype female MNHN Cop 15164 , Paratypes females MNHNCL Cop 15165 , Cop- 115166

Etymology: The specific name girellae , refers to the host generic name Girella laevifrons .

Female Description: Measurements based on 10 female specimens in micrometers. Cephalothorax (length 1,631 [ 1,513 –1,923], width 368 [282–436]) longer than trunk (length 1,102 [795–1,282], width 1,085 [641–1,461]); slightly curved. Elongated swelling at its base (aliform process), nipple-like projection; oriented anteriorly in line with the swelling. Head wide; well-developed dorsal shield. (Lateral view, Fig. 1A View FIGURE 1 : trunk suborbicular; genital process short, blunt.) Ovigerous females ( Fig. 5A View FIGURE 5 ) exhibit a trunk with a wider genital process (length 237 [103– 333], width 213 [128–256]). Egg sac, length 1,667 [ 1,333 –2,491], width 513 [512–561] (from three specimens). Antennules ( Fig. 5B View FIGURE 5 ): uniramous, four-segmented; basal segment longer than the others; whip on second segment; solus absent; distal armature ( Fig. 5C View FIGURE 5 ) comprises element 1, 2, 3 (few developed)(and digitiform setae 4, 5 (bifid) and 6. Antenna ( Fig. 5D View FIGURE 5 ): biramous; basipodite long (approximately three times the exopod length); exopod equipped with 9 spinules on the dorsal margin and 3 on the lateral surface; endopod bi-segmented, armed with three distal spines (spine 1 shorter than the others). Mandible ( Fig. 5E View FIGURE 5 ): with secondary dentition; dental formula: P1 S1, P1 S1, P1 S1, B3, plus very short basal teeth; first primary tooth very small. Maxillule ( Fig. 5F View FIGURE 5 ): bilobate; endite forming a lobe armed with a papilla, each bearing a seta of similar length; palp laterally located, with two setae (one slightly longer than the other), lacking additional armature. Maxilla ( Fig. 5A View FIGURE 5 ): median size; length 530 [385–641], width 175 [128–256]; biramous with fused rami; bulla cup-shaped. Maxilliped ( Fig. 6A View FIGURE 6 ): strong corpus; myxal area with one spiniform process; shaft slightly curved medially, with one seta on the basal third of the lateral surface; claw curved, with an annexed barb at the ventral base, reaching half the claw length.

Male Description: Cephalothorax and trunk fused ( Fig. 7A View FIGURE 7 ); body shape distinct from typical Clavellotis ; subtriangular outline; pronounced globose mid-dorsal area; genital process subtriangular, near the maxilliped. Antennules ( Fig. 7B View FIGURE 7 ): uniramous, four-segmented; whip on second segment; distal armature with short elemenst (labeled 1, 3, 2), digitiform process 4, and bifid seta 5. Antenna ( Fig. 7C View FIGURE 7 ): biramous; endopod longer than the exopod; endopod armed with a spine, a seta, and a pad of spinules on the distal surface; exopod with a dorsal spine and another on the distal border; spinules on the distolateral surface. Mandible ( Fig. 7D View FIGURE 7 ): with three primary, two secondary teeth, and five basal elements (P1, P1, S1, P1, S1, 5B). Maxillule ( Fig. 7E View FIGURE 7 ): ventrally located; endite with two papillae, each bearing a seta of equal length; palp laterally located with two unequal setae (the longer about twice the length of the shorter). Maxilla ( Fig. 7F View FIGURE 7 ): base elongated (suboval), bearing a short, strongly curved claw distally. Maxilliped ( Fig. 7G View FIGURE 7 ): corpus subrectangular; distal segment almost flat, not curved, and blunt.

Remarks

Clavellotis girellae sp. nov. can be separared from species bearing an elongated trunk—such as C. dubius sp. nov., C. characis , C. fallax , C. pagri , C. sargi , C. strumosa , and C. sebastidis —as well as from those species bearing a bilobated trunk (e.g., C. bilobata ). Instead, species with a subcircular trunk (namely, C. branchiostegui , C. dilatata , C. briani , and C. tarakihi ) must be distinguished based on several morphological features. For instance, C. branchiostegui has a medium-sized maxilla, whereas in the present species ( C. girellae sp. nov.) the maxilla is very short; they also differ in the length of the genital process, and notably, the male of C. girellae sp. nov. exhibits a globose dorsal projection that is absent in C. branchiostegui . In addition, C. briani possesses a long genital process and a long maxilla—characterized by an elongated form with a distal constriction that gives it a distinct appearance—whereas in C. girellae sp. nov. both the genital process and the maxilla are short and simple.Although the present specimens show considerable similarity to C. dilatata in terms of trunk shape, genital process, and cephalothorax disposition, the females display some differences compared to that species. Moreover, the antenna in C. dilatata bears an exopod with 10 spinules on its distal outer margin, while in C. girellae sp. nov. the exopod has nine spinules on its dorsal margin plus three additional spinules laterally. The endopod of C. dilatata has three elements of approximately equal size, whereas in C. girellae sp. nov. one element is notably shorter than the others. The maxillule of C. dilatata is distinguished by the presence of a row of spinules on the outer surface of the palp, a feature that is absent in C. girellae sp. nov. Similarly, the antennule in C. dilatata bears only tubercles 1 and 3, while in C. girellae sp. nov. it bears tubercles 1, 2, and 3. The maxilliped also differs between the two, as only C. dilatata has spinules on the ventral distal surface of the shaft. Furthermore, the male morphology of C. girellae sp. nov. is distinct from that of C. dilatata : the trunk in C. girellae sp. nov. exhibits a subcircular mid-dorsal prominence that is globose, appearing more subtriangular rather than the more suborbicular form observed in C. dilatata , and its maxilliped bears the distal segment without dentition, in contrast to the claw-like, denticulated distal segment found in C. dilatata . Although both species may appear very similar at first glance, these subtle morphological differences, combined with the observed molecular divergence, support the recognition of a new species that is very closely related to the type species of the genus.

In addition, C. tarakihi bears a very short genital process, whereas in C. girellae sp. nov. the genital process is of medium size. Moreover, in C. tarakihi the maxillule bears a palp with two setae—one short and the other very long—accompanied by a row of spinules on the posterolateral surface, while in C. girellae sp. nov. both setae on the palp are of equal size, lacking any additional armature. The mandible in C. tarakihi , as originally described, lacks secondary teeth, whereas C. girellae sp. nov. exhibits three secondary teeth. Finally, the male of C. tarakihi displays a normal dorsal surface, whereas in C. girellae sp. nov. a distinct globose projection is present.