Wellsopsyllus (Wellsopsyllus) egregius, Back, Jinwook & Lee, Wonchoel, 2014

Back, Jinwook & Lee, Wonchoel, 2014, Two new species of the genus Wellsopsyllus (Copepoda; Harpacticoida; Paramesochridae) from the Yellow Sea, Zootaxa 3895 (3), pp. 346-366 : 348-354

Wellsopsyllus (Wellsopsyllus) egregius sp. nov.

(Figures 2–6)

Type locality. Gosapo Beach on the Byeonsan peninsula, on the west (Yellow Sea) coast of Korea. Coordinates: 35° 39' 51 ''N, 126° 30' 35'′E ( Figure 1 ). Sediment type: sand. Salinity 33 psu.

Material examined. Holotype, 1♀ ( MABIK CR00218007) dissected on 7 slides. Paratypes: 1♂ ( MABIK CR00218008) dissected on 3 slides, 5 ♀♀ ( MABIK CR00218009) and 2 ♂♂ ( MABIK CR00218010) in 70% alcohol. October 3, 2010.

Description of female. Total body (Figure 2A–B) length, 462 µm (n = 6, mean = 460 µm), measured from anterior tip of rostrum of cephalic shield to posterior margin of caudal rami (Figure 2A–B)); largest width measured at posterior margin of cephalic shield: 51 µm. Body cylindrical, depressed dorsoventrally; urosome gradually tapering posteriorly (smallest width of last somite: 21 µm) with a weak hyaline frill.

Rostrum (Figure 2A), small, fused to cephalothorax, without sensilla. Cephalothorax (Figure 2A–B), bellshaped; pleural areas weakly developed and posterolateral angles rounded; posterior margin, smooth, with a distinct hyaline frill.

Genital somite and first abdominal somite (Figure 2A–B), completely fused forming a genital double-somite; genital field located mid-ventrally approximately halfway along the length of the genital double-somite. Copulatory pore ( Figure 5 B) located near posterior border of genital field, covered by a small process and enclosed within a depression. P6 ( Figure 5 B) represented by a small process with 1 bare and 1 unipinnate setae. Pseudoperulum, weakly developed (Figure 2A).

CR (Figure 2D1–D2), juxtaposed, approximately 2.8 times longer than greatest width, posterior inner margin acute, distal margin rounded inwardly, and with a small process near seta V. Each ramus armed with 6 setae: seta I bare; setae II bare; seta III blunt, ornamented with stout spinules; seta IV pinnate; seta V blunt, pinnate; seta VI not observed and probably represented by a small process; seta VII bi-articulate at base and arising sub-distally from inner dorsal surface.

A1 (Figure 2C), 8-segmented, short, robust. Segment-1 longest with a blunt process; segment-4 with a subcylindrical process with 1 long slender seta fused basally to aesthetasc; segment-6 with 1 slender bare seta arising from a ventral sub-cylindrical process. Armature formula: 1-[1 pinnate], 2-[7 bare + 2 pinnate], 3-[2 bare + 4 pinnate], 4-[1 bare + (1 + ae)], 5-[2 bare], 6-[2 bare], 7-[3 bare], 8-[4 bare + acrothek]; apical acrothek consisting of a well-developed aesthetasc fused basally to 2 slender setae.

A2 ( Figure 3 A), 4-segmented, comprising coxa, basis, 1-segmented exp, and 2-segmented free enp; coxa small and bare; basis approximately 1.7 times longer than wide, without any surface ornamentation; proximal endopodal segment with 1 pinnate abexopodal seta; distal endopodal segment ornamented with 2 rows of spinules on surface and armed with 1 lateral bare seta, 2 bare spine-like setae sub-distally, 5 geniculate distal setae, one of which was fused basally to long slender seta; exp 1-segmented, with 2 bare setae laterally, 1 bare seta at distal corner, and 1 bifid seta apically.

FIGURE 2. Wellsopsyllus (Wellsopsyllus) egregius sp. nov., female: (A) Habitus, dorsal; (B) habitus, lateral; (C) antennule; (D) D1: left caudal rami, dorsal; D2: seta VII.

FIGURE 4. Wellsopsyllus (Wellsopsyllus) egregius sp. nov., female: (A) P1; (B) P2; (C) P3; (D) P4.

FIGURE 6. Wellsopsyllus (Wellsopsyllus) egregius sp. nov.: (A) male habitus, dorsal; (B) male antennule; B1: segments 1 to 4; B2: segments 5 to 7; (C) female maxillule.

Mandible ( Figure 3 B1–B2), coxa with well-developed gnathobase bearing 1 small bare seta at the dorsal corner and 7 major blunt overlapping teeth; palp biramous, comprising basis, 1-segmented exp and 2-segmented enp; basis widening distally, without armature; exp with 2 distal bare setae; enp elongated, approximately 3 times as long as exp; enp-1 with 2 bare sub-distal setae; enp-2 with 6 basally fused bare setae at apex.

Maxillule (Figure 6C), praecoxal arthrite well developed, with 6 spines, 1 bare seta at distal corner, 1 slender seta on lateral margin, and 2 juxtaposed slender setae on anterior surface; coxa with cylindrical endite bearing 4 bare setae; basis cylindrical; endites fused, with 1 pinnate and 5 bare setae; exp 1-segmented, small, with 2 bare setae; enp 1-segmented, elongate, with 1 pinnate and 3 bare setae.

Maxilla ( Figure 3 C), syncoxa with 3 cylindrical endites; praecoxal and proximal endites with 1 pinnate and 1 bare setae; distal coxal endite with 1 bare and 2 pinnate setae; allobasis with 1 strong claw-like spine, 1 pinnate and 1 bare setae distally, and 1 pinnate seta near base of enp; enp 1-segmented, with 1 claw-like spine, 3 pinnate setae, and 1 bare seta distally.

Maxilliped ( Figure 3 D) 4-segmented, comprising syncoxa, basis, and 2-segmented enp; syncoxa and basis bare; enp-1 with 1 stout seta distally; enp-2 with 2 lateral bare and 2 geniculate setae.

P1 (Figure 4A), basis with 1 outer and 1 inner bare setae; exp-1 approximately 1.8 times longer than exp-2, the former with 1 long pinnate seta near outer distal corner and ornamented with a row of long spinules horizontally in middle of segment; exp-3 with 4 long pinnate setae distally; enp prehensile; enp-1 elongate, about 1.2 times longer than exp, bare, inner distal corner forming a small projection; enp-2 small, with 1 geniculate seta apically and ornamented with a row of spinules around outer distal margin.

P2–P3 (Figure 4B–C), basis with 1 outer bare seta and ornamented with 1 pore and 1 row of spinules in middle. exp 3-segmented; exp-1 and 2 with 1 outer spine; exp-3 with 1 spine and 1 geniculate seta; enp 1- segmented, small, without ornamentation, represented by a small process.

P4 (Figure 4D), basis with 1 outer bare seta and ornamented with 1 pore and 1 row of spinules in middle. exp 3-segmented; exp-1 and 2 with 1 outer spine at distal corner; exp-3 with 1 naked outer spine and 1 geniculate seta; enp 1-segmented, with 1 stout unipinnate apical seta.

Benp of P5 ( Figure 5 A) confluent, with 1 naked basal seta, an acute outer process, and one pore; fused endopodal lobes with a small bilobed process in middle; each endopodal lobe with 2 bare setae; exp clearly separated from benp, small, quadrilateral, with 2 bare and 1 pinnate setae.

Description of male. Body (Figure 6A), slightly smaller and more slender than female, body length 385 µm (measured from anterior margin of cephalic shield to posterior margin of caudal rami: n = 3, mean = 381 µm), largest width measured at posterior margin of cephalic shield: 44 µm; general body shape and ornamentation as in female except for separation of genital somite; additional sexual dimorphism in A1, P5, and P6.

A1 (Figure 6B1–B2), 7-segmented, subchirocer; armature formula: 1–[1 pinnate], 2–[8 bare + 2 pinnate], 3–[5 bare + 1 pinnate], 4–[1 bare + 1 pinnate], 5–[6 bare + 1 modified stout + (1 + ae)], 6–[4 bare], 7–[6 bare + acrothek], apical acrothek consisting of small aesthetasc fused basally to 2 bare setae.

P5 ( Figure 5 C), benp of P5 confluent, with 1 bare basal seta, 1 pore, and acute outer process; endopodal lobe flat without armature; exp discrete, with 2 bare and 1 pinnate setae.

P6 ( Figure 5 D), pair of P6 asymmetrical, not confluent; each P6 with 1 naked seta.

Etymology. The specific name ‘ egregius’ means ‘shocking’ in Latin and refers to the unusual shape of the caudal rami.

Figures

FIGURE 1. Distribution of the family Paramesochridae in Korea.

FIGURE 3. Wellsopsyllus (Wellsopsyllus) egregius sp. nov., female: (A) Antenna; (B) B 1: gnathobase of the mandible; B 2: mandibular palp; (C) maxilla; (D) maxilliped.

FIGURE 5. Wellsopsyllus (Wellsopsyllus) egregius sp. nov.: (A) female P 5; (B) female P 6 and genital field; (C) male P 5; (D) male P 6.