Doropygopsis novemsetifera ( 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 : 299-300

Doropygopsis novemsetifera ( Schellenberg, 1922) ( Figs. 200 , 201 )

Material examined. 1 ♀ (dissected and figured) from Polycarpamytiligera (Savigny, 1816) , Masa Bareika, Red Sea; 1 copepodid V ♀ (dissected) from Polycarpa nigricans Heller, 1878 , Ibo, Mozambique, 1995; 4 ♀♀ (MNHN-IU-2018-1846) from Pyura styeliformis Monniot F. & Monniot C., 2001 Palau (07°16.80 Ń, 134°25.92 É), depth 0.5 m, 06 April 2004; 3 ♀♀ (MNHN-IU-2018- 1847) and 1 dissected ♀ from Pyura gangelion (Savigny, 1816) , Ibo, Mozambique, 1995; 1 ♀ ((MNHN-IU-2009- 2471) and 1 dissected ♀ from Pyura vittata (Stimpson, 1852) , Raja Ampat, West Papua, Indonesia (00°27.289 Ń, 130°29.580 É), depth 1 m, 26 November 2007; 1 ♀ (MNHN-IU-2018-1848) and 1 dissected ♀ from Pyura pantex (Savigny, 1816) , Victoria, Seychelles, 1995.

DescriptionofFemale. Body ( Fig. 200A ) narrow. Body length variable, 5.6 mm long in figured specimen from Polycarpa mytiligera , 2.3-2.9 mm in specimens from other hosts. Prosome consistingof cephalosome and 4-segmented metasome; secondandthirdpedigerous somites with well-developed, rounded epimera: fourth pedigerous somite forming brood pouch, largely incorporatingfifth pedigerous somite. Freeurosome ( Fig. 200B ) slender, 5-segmented; genitalsomite short, 218×553 μm; 4 abdominalsomites 450×436, 450×407, 364×364, and 290×320 μm, respectively. Caudalramus ( Fig. 200C ) elongate, about 7.6 times longer than wide (662×87 μm) and 2.3 times longer than anal somite, distal margin with rounded ventral protrusion; armed with 6 small setae; outer proximal and dorsal setae positioned at 26 and 68% of ramus length, respectively; all setae naked.

Rostrum ( Fig. 200D ) tapering.Antennule ( Fig. 200E , Fig. 30 ) indistinctly 9-segmented; articulation between eight and ninth segments incomplete; sixth segment with 2 incomplete sutures on posterior side; armatureformula 3, 17, 5, 7, 10, 9, 3, 4+aesthetasc, and 7+aesthetasc; setae extremely crowded; 3 or 4 setae on proximal segments pinnate. Antenna ( Fig. 200F ) slender, 4-segmented, including short, unarmedcoxa; basis with 1 small vestigial seta distally; first endopodal segment with 1 inner seta subdistally; compound distal endopodal segment 4 to 5 times longerthan wide; armed with 10 smallsetae plus small terminal claw, about one-third as long as segment.

Labrum ( Fig. 200G ) with concave free posterior margin bearing setules on both sides; concavity largely occluded by broad posteromedian lobe bearing spinules on ventral surface and along posterior margin. Mandible with 6 teeth on coxal gnathobase ( Fig. 200H ); basis with 1 medial seta; exopod with 5 setae, distalmost seta shorter than other 4 and naked, or with minute spinules along margins; endopod with 4 and 10 setae on first and second segments, respectively. Paragnath ( Fig. 200I ) bearing small denticle mediodistally and ornamented with setules onmedial margin. Maxillule ( Fig. 200J ) with 10 setaeon arthrite, 1 broad-based seta on coxal endite, 2 unequal setaeon epipodite, and 4 setaeon exopod; endopod 2- segmented, with 5 setae on first segment and 4 setae on short second. Maxilla ( Fig.201A ) with10 setaeonsyncoxa (4, 1, 2, and 3 on first to fourth endites, respectively), 1 strong claw plus 2 setae on basis, and 1, 1, and 4 setae on first to third endopodal segments, respectively. Maxilliped ( Fig. 201B ) 3-segmented with 9, 1, and 4 setae on first to third segments, respectively; first segment ornamented with several oblique rows of minute spinules.

Legs 1–4 with 3-segmented rami ( Fig. 201 C-E). Inner coxal seta large in leg 1, but absent in legs 2–4. Outer setaon basis small in legs 1–4. Outer spine on first exopodal segment of leg 1 large, extending well beyond distal border of second exopodal segment; outer spine on second exopodal segment and first outer spine on third exopodal segment small, about one-third as long as outer spine on first segment. First exopodal segment of leg 4 with or without inner seta (probability about 50%, such variation observed even in single individual): first and secondendopodal segments lacking inner seta. Armature formula for legs 1–4 as in generic diagnosis.

Leg 5 ( Fig. 201F ) 2-segmented; protopod fused to somite, armed with 1 small outer seta but unornamented; free exopodal segment about 3.9 times longer than wide (232×60 μm), armed with broad distal and slender subdistal setae; ornamented with 4 oblique rows of minute setules on dorsomedial surface.

Copepodid V female. Bodylength 2.21 mm. Abdomen comprising 3 segments. Caudal ramus about 5.9 timeslongerthan wide. Antennule 9-segmented; armature formula 2, 15, 6, 7, 9, 5, 1, 4, and 11+aesthetasc. Antenna as in adult. Mandible with 6 teeth on coxal gnathobase; exopodwith 5 setae; endopodwith 3 and 9 setaeonfirst and second segments, respectively. Maxillule as in adult, except first endopodal segment bearing 4 setae. Maxilla with 3 setae on first endite of syncoxa, otherwise as in adult. Maxilliped 3-segmentedwith 7 (3+4), 1, and 4 setae on first to third segments, respectively. First exopodal segment of leg 4 with rudimentary inner seta, otherwise legs 1–5 with same armature as in adult.

Male. Unknown.

Remarks. Schellenberg (1922) recorded this species (as Doropygus novemsetiferus ) as an associate of Styela canopus Savigny, 1816 and Pyura gangelion (Savigny, 1816) in the Gulf of Suez. Illg (1958) transferred it to the genus Doropygopsis and Stock (1967) subsequently reported it from the Red Sea. The present record extends the known distributional range of D. novemsetifera to include the Indian Ocean south to Mozambique and east to the Seychelles, and the western Pacific Ocean from Palau to western Papua in Indonesia. The most distinctive feature of this species is the presence of 9 setae on the endopod of themaxillule ( Illg, 1958; Stock, 1967). The specific name is emended here to novemsetifera since Doropygopsis is feminine.

The antennule of D. novemsetifera carries numerous supernumerary setae on the more distal segments ( Fig. 30 ). The fifth segment (XXVII-XX) carries 10 setae where the maximum elsewhere in the family is 7; the sixth segment (XXI-XXIII) carries 9 setae where the maximum elsewhere is 4 setae plus 1 aesthetasc, the seventh segment (XXIV) carries 3 setae (maximum 2) and the eighth (XXV) carries 4 setae plus and aesthetasc. Ancestral segment XXV normally carries a maximum of 2 setae plus 1 aesthetasc in any copepod ( Boxshall & Huys, 1998), and the presence of 2 additional setae is shared with Paranotodelphys saccata and P. polycarpae ( Fig. 30 ).

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.

FIGURE 200. Doropygopsis novemsetifera (Schellenberg, 1922), female. A, habitus, right; B, urosome, ventral; C, left caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, paragnath; J, maxillule. Scale bars: A, B, 0.5 mm; C–F, H, 0.1 mm; G, I, J, 0.05 mm.

FIGURE 201. Doropygopsis novemsetifera (Schellenberg, 1922), female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4; F, leg 5. Scale bars: 0.1 mm.