Spheromolgus, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods associated with Ascidian hosts (Tunicata): Intramolgidae and Lichomolgidae, with descriptions of four new genera and 13 new species, Zootaxa 5013 (1), pp. 1-75 : 57

Spheromolgus gen. nov.

Diagnosis (female). Lichomogidae. Body cyclopiform. Prosome inflated. Urosome 5-segmented. Caudal rami with 6 setae. Rostrum well-developed. Antennule 7-segmented, with armature formula 4, 13, 6, 3, 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc. Antenna 4-segmented, with armature formula 1, 1, 4, and 3+3 claws. Labrum broad, with 2 posterior lobes. Mandible with moderately long distal lash; blade slightly broadened, with inner margin perpendicular to distal lash. Maxillule with 3 setae. Maxilla 2-segmented; basis with elongated, distal lash bearing long spinules, and armed with distinct inner and anterior setae. Maxilliped 3-segmented; terminal segment claw-like. Leg 1-3 with 3-segmented rami. Leg 4 with 3-segmented exopod and 2-segmented endopod. Leg 4 endopod small, armed with inner seta on proximal segment and 1 spine distally on distal segment. Armature formula for legs 1-4 as follows:

Coxa Basis Exopod Endopod

Leg 1: 0-1 1-0 I-0; I-1; III, I, 4 0-1; 0-1; I, 1, 4

Leg 2: 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 3

Leg 3: 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 2

Leg 4: 0-1 1-0 I-0; I-1; II, I, 5 0-1; 0, I, 0

Leg 5 consisting of dorsolateral seta on fifth pedigerous somite and 1-segmented free exopod armed with 1 spine and 1 seta distally. Leg 6 represented by 2 setae and 2 dentiform cusps on genital operculum.

Type species. Spheromolgus rarus gen. et sp. nov. by original designation.

Etymology. The name of the new genus is derived from Greek spher (=a ball) and – molgus, the suffix of many generic names in the Lichomolgidae . It alludes to the spherical cephalothorax of the female of the type species. Gender masculine.

Remarks. Spheromolgus gen. nov. has one inner seta on the proximal segment and one spine on the compound distal segment of the 2-segmented endopod of leg 4. This armature is shared with three existing genera in the Lichomolgidae , Botulosoma , aebruma, and Gelastomolgus . Two of these, Botulosoma and Gelastomolgus , have reduced armature on the anterior swimming legs, whereas aebruma has a complete armature on legs 1-3, as in Spheromolgus gen. nov. Nevertheless, the new genus can be separated from aebruma by the 3-segmented condition of the female maxilliped, which is only 2-segmented with a blunt distal segment in aebruma (as in Gelastomolgus and iẚchomolgẚdẚum), the mandible has a distal lash (cf. distal lash absent or very short in aebruma), and the maxilla has a large inner seta on the basis (cf. this seta is absent or rudimentary in aebruma). We consider that these differences support the recognition of Spheromolgus rarus gen. et sp. nov. as representing a new genus, distinct from aebruma.