Cerviniella permixta, Cho & Kim & Lee, 2023

Cho, Kyuhee, Kim, Jong Guk & Lee, Jimin, 2023, Two new species of Cerviniella Smirnov, 1946 (Copepoda, Harpacticoida, Aegisthidae) from the Yellow Sea, Korea, ZooKeys 1178, pp. 165-189 : 165

Cerviniella permixta sp. nov.

Figs 5 , 6 , 7 , 8

Type locality.

The Yellow Sea; 35°00'05.44"N, 125°59'44.49"E; 88.1 m depth.

Type material.

Holotype. One ♀ preserved in a vial with 80% ethanol (MABIK CR00253875); collected from the type locality, March 02, 2022. Paratypes. One ♀ (MABIK CR00253872) dissected on 10 slides, two ♀♀ (MABIK CR00253876) preserved in a vial with 80% ethanol, collection data as in holotype; J.G. Kim leg.

Description.

Female (based on the holotype and paratypes). Body length from anterior margin of rostrum to posterior margin of caudal rami (paratype, MABIK CR00253872, in lateral view, telescoping of somites not considered) 857 μm (range: 857-886 μm, n = 4, holotype: 861 μm).

Habitus (Fig. 5A, B ) subcylindrical, gradually tapering posteriorly, with unclear separation between prosome and urosome.

Prosome (Fig. 5A, B ) slightly longer than urosome, comprising cephalothorax (with completely fused first pedigerous somite) and three free pedigerous somites. Cephalothorax bell-shaped, slightly longer than wide, ~ 31% of body length; surface embossed with numerous minute dots (or denticles) and striped pattern (discernible under high resolution), covered with several sensilla and pores; rim with anastomosing patterns; ventro-posterior margins with row of fine spinules and posterior margin weakly serrate. Pedigerous somites bearing P2-P4 with several sensilla, minute spinules and pores as shown in Fig. 5A, B . Pleural areas of P2-bearing somite more extended than those of other prosomites, P2- and P3-bearing somites with pointed posterolateral corners; posterior margins distinctly serrate.

Urosome (Figs 5A, B , 6A ) comprising P5-bearing somite, genital double-somite, and three free abdominal somites; surface covered with striation and minute spinules (or denticles); posterior margins finely serrated except for anal somite, pore pattern on dorsal surface as indicated in Fig. 5A . Genital somite and third urosomite separated dorsally and laterally, but completely fused ventrally forming genital double-somite (Figs 5A, B , 6A ), with one pair of hook-like lateral projections on original genital somite. Genital apertures (Fig. 6A ) located far anteriorly; closed off by single plate, on both sides with an outer vestigial seta and an inner bare seta, representing P6 (Fig. 6A ). Copulatory pore located in the middle. Anal somite (Figs 5A, B , 6A ) slightly shorter than two preceding urosomites combined; as long as caudal rami; with one pair of sensilla dorsally and one pair of pores laterally; with semicircular operculum ornamented with minute spinules; lateral margin of anal opening with spinules row and a spinous process.

Caudal rami (Figs 5A, B , 6A ) cylindrical, ~ 4 × as long as greatest width, surface covered with stripes and fine spinules; with pairs of pores on dorsal and ventral surface; with seven setae: ventro-lateral seta I bare, short, inserted in proximal third of ramus, dorso-lateral seta II pinnate, ~ 1.5 × longer than seta I; seta III missing (this seta missing in all specimens), arising from outer subdistal corner; terminal setae IV and V well-developed, with internal fracture plane proximally, both setae fused basally, seta V longest (but damaged in all specimens); seta VI shortest, spiniform, located on ventro-posterior margin; tri-articulate seta VII plumose, issuing from dorsal surface subdistally.

Rostrum (Fig. 5A, C ) completely fused to cephalothorax, triangular, subdistally with one pair of sensilla and one ventral tube pore; apical tip blunt.

Antennule (Fig. 6B ) robust, short, seven-segmented, covered with numerous diminutive dots (or denticles) as shown in Fig. 6B . First segment largest. Third segment with one peduncle bearing a seta fused to an aesthetasc. Fourth to sixth segments small. Seventh segment subdistally with a pinnate seta fused to an aesthetasc. Armature formula: 1-[1 pinnate], 2-[5 pinnate + 3 spine], 3-[2 + 4 pinnate + 2 spine + (1 pinnate + ae)], 4-[1 + 1 pinnate + 1 pinnate spine], 5-[1 pinnate + 1 pinnate spine], 6-[2 pinnate], 7-[1+ 5 pinnate + (1 pinnate + ae)].

Antenna (Fig. 6C ) three-segmented, comprising coxa, allobasis, and one-segmented endopod. Coxa small, with long outer spinules. Allobasis elongate, covered with several group of minute spinules, outer margin with one group of setules, and inner margin with two rows of long setules and two rows of spinules; area close to the insertion of exopod swollen; with one subdistal abexopodal seta. Endopod distinctly shorter than allobasis, with one row of outer setules, one row of inner setules, and one row of minute distal spinules; lateral armature composed of one serrate spine and two pinnate setae; distal armature consisting of four serrate spines, one pinnate seta, one plumose seta, and one bare seta; outermost serrate spine fused basally to neighboring seta. Exopod four-segmented, covered with minute spinules; proximal segment longer than other segments, with two pinnate lateral setae; second and third segments each with one pinnate lateral seta; distal segment distally with one pinnate and one plumose seta.

Mandible (Fig. 7A ). Coxa well-developed, proximally with four rows of various-sized spinules and subdistally with one row of minute spinules; gnathobase well-developed, with one uni-cuspidate and four multi-cuspidate teeth, of which outermost tooth largest, and one pinnate seta. Palp biramous, consisting of basis, three-segmented exopod, and one-segmented endopod; basis covered with minute spinules, subdistally with one pinnate and three plumose setae, of which subdistal one distally bare and proximally plumose. Exopod shorter than endopod; exp-1 longer than other two distal segments combined, covered with minute spinules, with one small plumose seta laterally and one long plumose seta subdistally; exp-2 small, with one pinnate seta; exp-3 small, with three plumose setae distally. Endopod 1.4 × longer than exopod, laterally with one pinnate and two bare setae, and distally with one pinnate and six bare setae, of which two bare setae fused at base (indicated by arrowhead in Fig. 7A ).

Paragnaths (Fig. 7B ) (damaged during dissection process, one side figured) with well-developed chitinized lobes; distal margin with numerous spinules; posterior face with five strong spinules and one row of tiny spinules; lateral margin with tiny spinules.

Maxillule (Fig. 7C ). Praecoxa ornamented proximally with several rows of outer spinules and subdistally with three rows of anterior spinules and two rows of posterior spinules; arthrite well-developed, with two juxtaposed pinnate setae anteriorly (one missing seta indicated by the dotted line in Fig. 7C ), seven spines and three pinnate setae distally, and two pinnate setae posteriorly (one missing seta indicated by the dotted line in Fig. 7C ); posterior surface with several rows of spinules. Coxa with one row of outer spinules and three rows of posterior spinules; endite cylindrical, with one pinnate and five bare setae subdistally or distally. Basis broad, with several rows of posterior spinules and ten distal setae. Exopod represented by one pinnate and two plumose setae. Endopod completely fused basally to basis, represented by three setae.

Maxilla (Fig. 7D ). Syncoxa large, with numerous rows of spinules anteriorly and posteriorly and one row of long outer setules; with four endites: proximal praecoxal endite separated basally from syncoxa, with four pinnate setae distally; distal praecoxal endite rudimentary, represented by three bare setae; proximal coxal endite cylindrical, with three bare setae distally; distal coxal endite also cylindrical, with one pinnate spine and two setae distally (one bare and one pinnate). Allobasis with one unipinnate stout spine and two bare setae distally; inner part drawn out into a curved strong claw accompanied by one unipinnate stout spine and two bare setae. Endopod small, three-segmented; first segment with one bare and one geniculate seta; second segment with two geniculate setae; distal segment with one geniculate and three bare setae.

Maxilliped (Fig. 7E ) three-segmented. Protopod elongate, with two and three rows of long setules along outer and inner margins and numerous rows of spinules on anterior and posterior surfaces; with four endites: syncoxal endites represented proximal to distal by two pinnate spines, three pinnate spines, and one pinnate spine and one plumose seta; basal endite represented by one pinnate spine and one plumose seta. Endopod two-segmented, with one row of outer setules on first segment, the latter with one plumose seta; second segment with two pinnate spines distally, and one unipinnate and one plumose seta laterally.

P1 (Fig. 8A ). Intercoxal sclerite transversely elongated and narrow, with weak surface reticulation distally. Praecoxa (damaged) small, with anterior and distal spinules. Coxa wide, with various-sized spinules anteriorly and distally. Basis wide, somewhat larger than coxa, with one anterior pore and several rows of spinules anteriorly and distally; outer setophore with one row of anterior spinules and one plumose seta; inner distal corner produced, with one pinnate seta slightly exceeding end of exopod. Exopod one-segmented, elongate, with rows of outer and inner setules and two groups of anterior spinules, and several groups of spinules at bases of outer and distal setae; with two plumose inner, two pinnate apical, and five pinnate outer setae. Endopod one-segmented, ~ 1/2 exopod length, with two rows of outer setules and one outer and two apical setae.

P2 (Fig. 8B ) larger than other legs, anterior surface covered with striated patterns (not figured). Intercoxal sclerite well-developed, cordiform, slightly concave distally, with surface reticulation, two pairs of anterior spinular rows and one pair of distal setular rows. Praecoxa small, triangular, with one row of minute spinules anteriorly and one row of minute spinules distally. Coxa large, wide; anterior surface with one pore, one row of large spinules and numerous rows of minute spinules; distal margin with one row of minute spinules. Basis large, with numerous rows or groups of fine spinules anteriorly and one row of setules distally; distal margin with small process between rami, and outer margin with one pore and one plumose seta. Exopod one-segmented, expanded distally; with five serrate outer spines, of which proximal third one shortest, one serrate apical spine, one pinnate apical seta, and four plumose inner setae; outer and distal margins with one blunt and five acute processes at bases of spines; anterior surface with one small pore and several rows of spinules; outer margin with one row of fine spinules and one row of setules; posterior surface with several rows of spinules (not figured). Endopod two-segmented, reaching distal fourth of exopod; enp-1 with several minute anterior spinules, two rows of outer setules, one plumose inner seta and one distal pore; outer corner drawn out into a chitinous process with weakly bifid tip; enp-2 with one plumose outer seta, one plumose apical seta, one small pinnate apical spine, and four plumose inner setae, and two anterior pores; distal and outer margins each with two acute processes.

P3 (Fig. 8C ) smaller than P2; anterior surface covered with striated patterns (not figured). Intercoxal sclerite well-developed, subrectangular, with surface reticulation and one row of long distal setules. Praecoxa small, with one row of minute spinules distally. Coxa large, with one large pore, one group of spinules and one row of minute spinules on anterior surface, and one row of minute spinules along distal margin. Basis larger than coxa; anterior surface with one large pore and several rows of fine spinules; outer setophore with one long plumose seta; inner margin with one rounded protrusion bearing one row of setules; distal margin with one small process between rami and one row of setules. Exopod one-segmented, expanded, with five serrate outer spines, of which proximal third one shortest, one serrate apical spine, one pinnate apical seta, and three plumose inner setae; outer and distal margins with four acute and three small processes; anterior surface with several fine spinules and one small pore; posterior surface with several spinules (not figured); inner and outer margins with one and two rows of setules, respectively. Endopod two-segmented, slightly exceeding 1/2 of exopod length; enp-1 as in P2, with outer chitinous process, two rows of outer setules, and one plumose inner seta; enp-2 elongate, 3 × as long as wide, with one row of outer setules, one pinnate apical seta, and one plumose outer seta.

P4 (Fig. 8D ) visibly reduced, composed of outer setophore and exopod, fused basally to supporting somite. Outer setophore larger than exopod, covered with minute anterior spinules, with one long pinnate seta apically and one small inner protrusion subapically. Exopod one-segmented, small, with one pinnate apical and one pinnate outer seta. Endopod absent.

Armature formulae of P1-P4 as follows:

P5 (Fig. 8E ) fused basally to supporting somite as in C. bisegmenta sp. nov. Outer setophore cylindrical, covered with small denticles, with one long pinnate seta. Exopod small, fused basally to baseoendopod, covered with small denticles, with one plumose apical and one pinnate outer seta; apical seta 1.8 × longer than outer seta.

Male. Unknown.

Etymology.

The specific name Cerviniella permixta is derived from the Latin adjective permixtus, meaning ‘mixed’ or ‘confused’, and refers to the fact that several diagnostic characteristics of Cerviniella species are mixed in this species. It is in the nominative singular. Gender: feminine.

Remarks.

Cerviniella permixta sp. nov. lacks a P4 endopod and is placed in the Cerviniella mirabilipes group as C. bisegmenta sp. nov. described above. This new species can be distinguished from C. bisegmenta sp. nov. on the basis of several morphological differences. Cerviniella permixta sp. nov. is characterized by the presence of numerous minute pits on the cephalothorax surface, whereas C. bisegmenta sp. nov. is characterized by numerous minute dots or denticles. Cerviniella permixta sp. nov. has a blunt rostral tip, whereas C. bisegmenta sp. nov. has a concave tip. The antennule has seven segments in C. permixta sp. nov. and five segments in C. bisegmenta sp. nov. The P1enp-1 lacks the inner seta and P3enp-2 has two setae in C. permixta sp. nov., whereas the P1enp-1 has an inner seta and P3enp-2 has one seta in C. bisegmenta sp. nov. The caudal ramus of C. permixta sp. nov. is relatively long, with a 4-fold length relative to width, compared with a 1.7-fold length for C. bisegmenta sp. nov.

In the Cerviniella mirabilipes group, the species with a seven-segmented antennule are C. lagarderei , C. langi (but illustrated as six-segmented in the original description ( Bodin 1968: pl. III); see discussion below), C. mirabilipes , C. talpa , as well as C. permixta sp. nov. However, C. permixta sp. nov. is different from these four species in several characteristics. First, C. permixta sp. nov. has two setae on the distal exopodal segment of the antenna, compared with three setae in C. langi . Second, C. permixta sp. nov. has a three-segmented mandibular exopod, compared with a one-segmented mandibular exopod in C. mirabilipes and four-segmented in C. lagarderei and C. langi . Third, the P1enp-1 of C. permixta sp. nov. has three setae, compared with six in C. lagarderei and C. talpa , and seven in C. langi . Fourth, the P2enp-2 apical margin has a spine-like element in C. permixta sp. nov., compared with a seta-like element in the remaining four species. Fifth, the P3enp-2 of C. permixta sp. nov. has two setae, compared with four setae in C. langi and C. talpa , and three setae on the one-segmented P3 endopod in C. lagarderei . Finally, the reduced P4 exopod of C. permixta sp. nov. has two setae, compared with four setae in C. talpa and five setae in C. mirabilipes ; C. lagarderei has the well-developed and two-segmented ramus with ten setae/spines.

Figures

Figure 5. Cerviniella permixta sp. nov. Female. Holotype (MABIK CR 00253875) A habitus, dorsal view B habitus, lateral view; Paratype (MABIK CR 00253872) C rostrum. Scale bars are in μm.

Figure 6. Cerviniella permixta sp. nov. Female. Paratype (MABIK CR 00253872) A urosome B antennule C antenna. Scale bars are in μm.

Figure 7. Cerviniella permixta sp. nov. Female. Paratype (MABIK CR 00253872) A mandible B paragnaths, anterior, one side C maxillule D maxilla E maxilliped. Scale bars are in μm.

Figure 8. Cerviniella permixta sp. nov. Female. Paratype (MABIK CR 00253872) A P 1, anterior B P 2, anterior C P 3, anterior D P 4 E P 5. Scale bars are in μm.