Paranotodelphys Schellenberg, 1922

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 : 48

Genus Paranotodelphys Schellenberg, 1922

Diagnosis. Female body with internal brood pouch extending from anterior margin of fourth pedigerous somite backwards and incorporating fifth pedigerous somite. Freeurosome 5-segmented infemale consistingof genitalsomiteand 4 abdominalsomites; 6-segmented in male. Rostrum well-developed, variable in form. Female antennule typically 9-segmented: segmental fusion pattern I-II, III-XI, XII-XIV, XV-XVI, XVII-XX, XXI-XXIII, XXIV, XXV, XXVI-XXVIII; but with maximum of 11 segments (see below). Male antennule typically 9-segmented and non-geniculate; segmental fusion pattern of 9-segmented antennule I-II, III-XI, XII-XIV, XV-XVI, XVII-XX, XXI-XXIII, XXIV, XXV, XXVI-XXVIII. Antenna typically consisting of coxa, basis, first endopodal segment with or without inner seta; compound distal segment (representing fused second and third ancestral segments) bearing terminal claw; some species with allobasis (comprising basis and fused first endopodal segment); exopod represented by 2 setae. Mandible with welldeveloped coxalgnathobaseand biramouspalp armed with 1 seta on basis, 5 setae on exopod, and typically with 2 or 3 and 7 to 9 setae on first and second segments, respectively; rarely with 4 and 10 setae as in P. molgulae n. sp. Maxillule with 7 to 10 setae on arthrite, 1 on coxal endite, 2 on epipodite, and 1 to 3 on medial margin of basis; exopod unsegmented with 4 setae distally; endopod 2-segmented or unsegmented, armed with total of 4 to 6 setae. Maxilla 5-segmented, syncoxal enditic formula 3/4, 1, 2, 3, or reduced; basis typically with 3 setal elements (1 claw-like); 3-segmented endopod with setal formula 1, 1, 3. Maxilliped 2- or 3-segmented; first segment armed with 9 setae; second segment typically unarmed, with bulbous swelling distally; third segment with 2 or 3 setae; distal segments fused in some species. 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	30-1	1-0	I-1; I-1; III, I, 50-1; 0-2; 1, 2, 3	50-1; 0-2; 1, 2, 3
Leg 4	0-0/1	1-0	I-1; I-1; II, I, 5	0-1; 0-2; 1, 2, 2

Inner coxal seta on leg 4 lost in some species. Leg 5 consisting of 2 papillae, each bearing single seta element, rarely with exopodal papilla defined as small free segment.

Type species. Paranotodelphys scutiformis Schellenberg, 1922 by original designation.

Remarks. The main feature differentiating Paranotodelphys from Notodelphys is the reduced form of the female fifth leg, which comprises 2 small papillae each bearing an apical setal element. The outer papilla carries the outer protopodal seta and the inner papilla represents the exopod. In some species the exopodal papilla is defined as a distinct segment. In contrast, the fifth leg of Notodelphys species always retains a free exopodal segment bearing 2 setal elements, while the protopodal segment can be either distinct or incorporated into the somite.

There are also differences in the segmentation of the female antennule, which is typically reduced in Paranotodelphys species compared to Notodelphys species, but there is some overlap in the expression of this character: the female antennule is typically 9-segmented in Paranotodelphys species compared to typically 15- segmented in Notodelphys species ( Fig. 30 ), but the former genus includes species with an 11-segmented antennule (e.g. P. polycarpae sp. nov.) whereas the latter includes species with as few as 10 segments (e.g. N. aurantiaca ). Many species of Paranotodelphys have an allobasis on the antenna compared to separate basis and first endopodal segments as in Notodelphys species, but a few Paranotodelphys species retain these segments as separate (e.g. P. scutiformis ). The ranges of states exhibited by other mouthparts are similar in Paranotodelphys and in Notodelphys species, although the maxilla of the former typically has 3 setae on the basis (one of which may be claw-like in some species) whereas in the latter the basis typically bears a well developed curved claw plus 2 setae.

Thegenera Paranotodelphys and Notodelphyopsis are closely related and share many character states. The main difference between them is in the urosomal segmentation of the female: the freeurosome is 5-segmented in the former genus and 4-segmented in the latter ( Illg, 1958; Marchenkov & Boxshall, 2003). The urosome comprises the genital somite plus four free abdominal somites in Paranotodelphys , whereas it comprises a genital double-somite and three free abdominal somites in Notodelphyopsis . Paranotodelphysillgi Marchenkov & Boxshall, 2003 and P. unguifer Kim & Moon, 2010 both exhibit the Notodelphyopsis - type urosome and therefore these two species are here transferred to the genus Notodelphyopsis as Notodelphyopsis illgi ( Marchenkov & Boxshall, 2003) comb. nov. and Notodelphyopsis unguifer (Kim & Moon, 2010) comb. nov.

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.