Procampodelphys bidentatus, Kim & Boxshall, 2020

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 : 583-585

Procampodelphys bidentatus gen. et sp. nov.

( Figs. 391 , 392 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21425 ) , paratype (intact ♀, MNHN-IU-2014-21426), and dissectedparatype (♀, figured) from Lissoclinum taratara Monniot F. & Monniot C., 1987 (MNHN-IT-2008-4990 = MNHNA 2/ LIS /162), Cape Rodney Pass, Papua New Guinea (10°15.66’S, 148°22.27’E), depth 31 m, 11 June 1998.

Etymology. The specific name is from the Latin bi (=two) and dentat (=toothed), and refers to the presence of the two small denticles on the distal margin of the mandibular gnathobase.

Descriptionoffemale. Body ( Fig. 391A ) caterpillarlike, cylindrical, curved ventrally, with surface densely covered with fine setules (omitted in Fig. 391A ). Body length 2.47 mm; body width 0.64 mm across posterior part of prosome. Prosome gradually broadening posteriorly; cephalosome ( Fig. 391B ) small, weakly defined from metasome. Metasome (trunk) unsegmented, but with constriction between first pedigerous somite and remaining part of metasome; second to fourth pedigerous somites forming brood pouch. Free urosome ( Fig. 391C ) small, slightly wider than long (200×210 μm), occupying only 8% of body length, and 3-segmented. First urosomite (genital double-somite) much wider than abdomen, with transverse suture line (or wrinkle) on ventral surface. Free abdomen 2-segmented; anal somite setulose. Caudal rami ( Fig. 391C ) short, setulose, about 60×50 μm; armedwith 4 smallsetae (1 lateral and 3 distal).

Rostrum ( Fig. 391B ) large, shield-like, with parallel lateral margins and convex distal margin, surface densely covered with fine setules. Antennule ( Fig. 391D ) small, 84 μm long, curved, about as long as wide, 2-segmented, secondsegment much smaller than first: armed with 20 and 9 setae on first and second segments, respectively, and ornamented with numerous setules (not shown in Fig. 391D ). Antenna ( Fig. 391E ) 3-segmented; coxa and basis unarmed; unsegmented endopod about 3.8 times longer than wide (61×16 μm), slightly longerthan basis, and ornamented with minute spinules along inner surface: armed with 2 subdistal and 2 distal setae plus small terminal claw, about quarter of length of endopod.

Labrum ( Fig. 391F ) slightly wider than long, narrowing distally, with rounded, setulose distal margin. Mandible ( Fig. 391G ) consistingof coxa and palp: coxal gnathobase with linear, pectinate medial margin, and 2 small denticles on convex distal margin; palp armed with 1 small setaon basis, 4 large setae on exopod, and 1 and 4 setae, respectively on first and second endopodal segments; articulations incomplete or obscure between basis and rami and between endopodal segments. Maxillule ( Fig. 391H ) consisting of precoxa and lobate, unsegmented palp; arthrite of precoxa extending beyond palp and armedwith 4 setae; palp with 5 large setae. Maxilla ( Fig. 392A ) distinctly 3-segmented, consistingof syncoxa, basis, and unsegmented endopod; armedwith 2 setaeon syncoxa, 1 setaon basis, and 3 setaeon endopod. Maxilliped ( Fig. 392B ) as unsegmented lobe armed with 5 large setae and 1 small seta on medial margin; distalmost seta markedly swollen, densely setulose on distal surface, with slender flagella-like, distal part; 2 proximal setae pinnate, 3 middle setae naked.

Legs 1–3 ( Fig. 392 C-E) bilobed, densely covered with setules, consistingof protopodal region, larger outer lobe (exopod), and smaller inner lobe (endopod); protopodal region with 1 seta on outer margin; protopodal region of leg 1 also with inner seta (originally inner distal seta on basis). Endopodal lobe of leg 1 tipped with 2 setae; endopodal lobe of legs 2 and 3 lacking seta. Outer lobe with 7 setae in leg 1, 1 seta distally in leg 2, but lacking setae in leg 3. Leg 4 ( Fig. 392F ) represented by small lobe tipped with 1 seta. Legs 5 and 6 absent.

Male. Unknown.

Remarks. Procampodelphys bidentatus gen. et sp. nov. resembles P. biramus ( Stock, 1967) comb. nov.: they share an identical form of mandibular gnathobase and have very similar caudal rami. In addition, both species have identical setation patterns on the maxillule, maxilla, and maxilliped. These two species can be distinguished by the presence in P. biramus of a dorsal tubercle on the first pedigerous somite, by the longer 4- segmented urosome, by the unsegmented antennule, the obscurely segmented maxilla, and the biramous condition of leg 4. In contrast, P. bidentatus gen. et sp. nov. lacks a dorsal tubercle on the first pedigerous somite, has a short 3-segmented urosome, a 2-segmented antennule, a distinctly 3-segmented maxilla, and a unilobate leg 4. The new species was collected off Papua New Guinea whereas P. biramus was originally recorded as an associate of the ascidian Didemnum candidum Savigny, 1816 in the Red Sea ( Stock, 1967).

Figures

FIGURE 391. Procampodelphys bidentatus gen. et sp. nov., female. A, habitus (showing nauplii within brood chamber), right; B, cephalosome and leg 1, ventral; C, urosome, ventral; D, antennule (setules omitted); E, antenna; F, labrum; G, mandible; H, maxillule. Scale bars: A, 0.2 mm; B, C, G, 0.05 mm; D–F, H, 0.02 mm.

FIGURE 392. Procampodelphys bidentatus gen. et sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 3; F, leg 4. Scale bars: A, B, 0.1 mm; C–F, 0.02 mm.