Pygodelphys Illg, 1958

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 92-93

Genus Pygodelphys Illg, 1958

Diagnosis. Female body with internal brood pouch extending from anterior margin of fourth pedigerous somitebackwardsand incorporatingfusedfifthpedigerous somite. Free urosome 5-segmented in female consisting of genitalsomiteand 4 freeabdominal somites, and 6- segmented in male. Rostrum well-developed, variable in form. Female antennule typically 9- or 10-segmented: segmental fusion pattern for 9-segmented antennule I-II, III-XI, XII-XIV, XV-XVI, XVII, XVIII-XX, XXI-XXIII, XXIV, XXV-XXVIII ( Fig. 30 ). Male antennule typically 9- or 10-segmented; non-geniculate; segmental fusion pattern usually as in female. Antenna typically consisting of coxa, basis, first endopodal segment with or without inner seta, and compound distal segment (representing fused second and third ancestral segments) bearing terminal claw; some species with allobasis (comprising basis plus first endopodal segment fused): exopod represented by 2 setae.

Mandible with well developed coxal gnathobase and biramous palp armed with 1 setaon basis, 5 setae on exopod, and typically with 4 and 10 setae on first and second segments, respectively, or reduced to 2 and 8/9. Maxillulewith 9 setae on arthrite, 1 on coxal endite, 2 on epipodite, and 3 on medial margin of basis; exopod unsegmented with 4 setae distally; endopod 2-segmented or unsegmented, armed with total of 5 or 6 setae. Maxilla 5-segmented with 10 setaeonsyncoxa (enditic formula 3/4, 1, 2, 3); basis with clawplus 2 setae; 3-segmented endopod with setal formula 1 1, 3/4. Maxilliped 2- segmented; first segment typically armed with 9 setae; second segment with 2 setae. Legs 1–4 biramous with 3- segmented rami; armatureformula typically:

	Coxa Basis Exopod			Endopod
Leg 1	0-1	1-I	I-1; I-1; III, I, 4	0-1; 0-1; 1, 2, 3
Legs 2 & 30-1		1-0	1-1; 1-1; 3, 1, 5	0-1; 0-2; 1, 2, 3
Leg 4	0-1	1-0	1-1; 1-1; 2, 1, 5	0-1; 0-2; 1, 2, 2

Leg 5 typically consisting of 2 papillae, each bearing single setal element; exopod expressed as free segment in some species; rarely leg absent.

Type species: Pygodelphys aquilonaris Illg, 1958 by original designation.

Remarks. The key features of the genus, as diagnosed by Illg (1958), are the combination of a 9- to 10-segmented antennule of the female, the 2-segmented maxilliped bearing 9 and 2 setae on proximal and distal segments, respectively, the presence of setiform elements (rather than spines) on outer margins of the posterior swimming legs, and the reduction of the fifth leg to two setiform papillae. Illg (1958) designated his new species P. aquilonaris as the type species of Pygodelphys and transferred three other species from Doropygus , as P. antarctica ( Schellenberg, 1922) , P. novaeseelandiae ( Schellenberg, 1922) and P. lamellipes ( Schellenberg, 1922) . Afifth species, P. patriciae Stock, 1967 , was added later by Stock (1967).

Figures

FIGURE 30. Schematic comparison of antennular segmentation patterns in selected notodelphyid taxa. Roman numerals mark ancestral segments, Arabic numerals indicate number of setae on each segment/compound segment. ae = aesthetasc. Supernumerary setae are identified by reference to the observed maximum setal number known within the Copepoda (see Boxshall & Huys, 1998). Supernumerary setae are present on segments III–XI, XII–XIV, XV–XVI, XXIV and XXV of Paranotodelphys polycarpae, on segments III–XI, XII, XV–XVI, XXI–XXIII, XXIV, XXV and XXVI–XXVIII of P. saccata, and on segments XVII–XX, XXI–XXIII, XXIV, and XXV of Doropygopsis novemsetifera.