Caprella serenae, Peart & Woods, 2025

Caprella serenae sp. nov.

( Figs. 1–2 View FIGURE 1 View FIGURE 2 , 16–18 View FIGURE 16 View FIGURE 17 View FIGURE 18 , Appendix 1)

Type material. Holotype: NIWA 155339 View Materials ( MITS 72042 ), male (14 mm), TRG23229, Tauranga , North Island, New Zealand, 37°38.1144’S 176°10.5024’E, depth not known, found on swing moorings during shore search, 19/07/2016 GoogleMaps . Paratypes: NIWA 155340 View Materials , male (11 mm) ; NIWA 155341 View Materials , female (8 mm), same collection data as holotype GoogleMaps .

Other material examined. NIWA 155342 View Materials , more than 100 specimens, stn Z18761, Wilson Bay, Coromandel, North Island , New Zealand, 36°53.25’S 175°25.5498’E, on rope, 1–2 m, coll GoogleMaps . R. D’Archino & W. Nelson, 10/10/2020 .

Etymology. The species is named for Dr Serena Keeler of NIWA, who has guided and encouraged the senior author in understanding New Zealand caprellids in a biosecurity context and who originally provided the funding for describing this material.

Diagnosis. Head with long, subacute, narrow triangular projection (reaching ½ of antenna 1 article 1), directed forward with ventrally directed tip; body robust otherwise without projections. Antenna 1 slightly shorter than ½ of body (0.4 ×); peduncle articles 1–2 not inflated in male, sparsely setose, longer than flagellum. Antenna 2 shorter than antenna 1 (0.7 ×), bearing long dense setae on ventral margin. Mandible without palp. Gnathopod 1 robust, with palmar margin of propodus setose with one proximal grasping spine; palm somewhat straight; dactylus serrate. Gnathopod 2 in male arising slightly anteriorly to the mid-point of pereonite 2; basis approximately ½ the length of propodus and 0.4 × of pereonite 2; palmar region of propodus concave, slightly setose with distal rectangular projection and slight proximal spiniform process; dactylus strong, apex pointed and constricted medially with distal end slightly serrate. Gnathopod 2 in female inserted distally on pereonite 2; palm of propodus sinuous. Gills rounded and quite large and inflated in male, maximum diameter half of length of pereonite 4. Gills oval to rounded and smaller in female. Pereopods 3 and 4 absent. Pereopods 5–7 increasing in length posteriorly; palmar margin of propodus convex bearing short, robust and slender setae with two median grasping spines.

Description. (Based on holotype male, 9.5 mm, NIWA 155339). Body: head anterodistal margin produced to form anteriorly directed tooth. Head fused with pereonite 1, suture present and visible. Pereonite smooth, no dorsal projections; pereonite 4 without distal hump. Ratio of lengths pereonites 1 (not including head) 1: 3.6: 3: 2.9: 2.4: 1.6: obscured. Head. Antenna 1 0.35 × body (approximately); peduncular article 2 longest, 1.6 × article 1, 1.9 × article 3; flagellum 0.4 × peduncular length with 12 articles. Antenna 2 0.7 × antenna 1 length; peduncular article 4 subequal in length to article 5 (0.96 ×). Mouthparts: lower lip inner plate rounded. Mandible right incisor with four teeth, lacinia mobilis with five teeth followed by two plumose setae. Mandible left incisor with four teeth, lacinia mobilis with five toothed teeth followed by three plumose setae, molar distinct. Maxilla 1 outer plate with eight apical tooth-like robust setae; palp two-articulate; article 2 longer than article 1 (7.8 ×) with six apical robust setae and 15 medial and lateral slender setae. Maxilla 2 inner plate broad with truncated apex, with 13 mostly apical slender setae; outer plate rounded/truncated apically with nine apical slender setae, inner plate shorter than outer plate. Maxilliped inner plate with 14 slender setae on entire distal margin and along distal ½ of inner margin; outer plate 1.5 × inner plate with five robust setae on inner margin, slender setae both laterally and apically; palp four-articulate, article 3 longest, setose along entire inner margin of articles 1–3; dactylus inserted apically, no setose lobe/ hood apically, fine hair-like setae along length medially, smooth tip. Gnathopod 1 basis subequal to ischium, merus, and carpus combined, small rounded posterodistal lobe present; merus produced to form rounded, setose posterior lobe; carpus subtriangular, densely setose on posterior lobe and across whole article, posterior lobe small, rounded, shorter than merus lobe; propodus subtriangular to subovoid, length 1.4 × width, setae along anterior margin; palm beginning at intersection of posterior margin and carpus; proximal defining corner equipped with pair of smooth robust setae (grasping spines) followed by ca. 12 setae along palm, palm serrated; dactylus weakly curved, inner margin rounded serrated, small setae along both inner and outer margins, simple tip; medial row of small conical robust setae ¾ length of dactylus. Gnathopod 2 basis anterior margin lined with rounded serrations, medial surface covered in small protuberances, basis produced to form triangular flange; ischium 0.23 × basis, without anterior distal triangular lobe; propodus longer than wide (length 1.5 × width); anterior margin with protuberances and small setae and on long seta; palm beginning ⅓ along posterior margin, proximal defining tooth long without robust setae, apically without grinding surface but with 2 slender setae; palm with predactylar rectangular shelf/projection, row of small setae along palm; dactylus outer margin with small setae along entire margin, inner margin serrated and sinuous. Gill 3 length 0.6 × pereonite 3; gill 4 subequal to gill 3. Pereopod 5 basis 0.5 × propodus, posterior margin serrated and expanded distally to form subacute flange; ischium 0.3 × basis; merus 1.1 × basis, anterior margin lined with slender setae, posterior margin produced to form subacute setose lobe; carpus 1.05 × basis, anterior margin lined with slender setae, posterior margin produced to form subacute setose lobe; propodus longest, with paired combed robust setae 0.25 along posterior margin on rounded corner, palm concave lined with 15 slender setae; propodus posterior margin lined with setae and serrated; propodus length 1.7 × width; dactylus long, reaching to defining corner, curved, inner margin highly textured with fringe of small setae, outer margin with setae. Pereopod 6 slightly longer than pereopod 5, similar structure to P5; propodus length 1.6 × width; dactylus inner margin with grinding surface. Pereopod 7 similar to pereopods 5 and 6; propodus posterior margin lined with slender setae; length propodus 1.75 × width.

Paratype (mature female, NIWA 155341, 8 mm). Ratio of pereonites 1–7 (not including head) 1: 4.2: 4.5: 4.4: 2.8: 1.8: 2.3. Antennae 1 slightly shorter than ½ body. Antenna 1 slender; peduncle article 2 longest, 1.5 × article 1, 2.25 × article 3; article 1 longer than article 3 (1.5 ×); flagellum 8 articles, flagellum shorter than peduncle. Antenna 2 reaching past the peduncle of antenna 1, and to ⅔ length of flagellum. Gnathopod 1 basis shorter than ischium, merus, carpus combined (0.75 ×); carpus subtriangular, setose on broadly rounded posterior lobe; propodus subtriangular, length 1.5 × width, without setae along anterior margin; palm beginning ⅛ along posterior margin; proximal defining corner, acute and equipped with pair of smooth robust setae followed by ca. 20 setae along serrated palm; dactylus weakly curved, serrate inner margin, with cusps near the tip. Gnathopod 2 basis anterior margin serrated, strongly produced to form large triangular flange; ischium 0.14 × basis, without lobe; propodus longer than wide (length 1.6 × width); palm beginning ¼ along posterior margin, proximal defining corner with two smooth robust setae; palm setose and serrated, with two subacute projections situated on distal ½ of palm, dactylus inner margin distally serrate and lined with small setae, outer margin with small setae and weakly serrate.

Distribution. Tauranga, North Island, New Zealand

New Zealand biosecurity status. Native.

Genbank Accession Numbers: SUB14807890 View Materials M06 Cserenae COI PQ522030 ; SUB14807890 View Materials M07 Cserenae COI PQ522031 ; SUB14807870 View Materials M06 Cserenae nSSU PQ521242 ; SUB14807870 View Materials M07 Cserenae nSSU PQ521243 .

Remarks. Caprella serenae sp. nov. belongs to the C. penantis species complex, along with C. novaezealandiae . A table of differences and similarities is provided ( Table 2). This species can be confused with C. novaezealandiae but can be separated by the presence of strongly rugose pereopods and the proportions of the pereonites, pereonite 2 of C. serenae 1.5 × pereonite 3 whereas pereonite 2 of C. novaezealandiae is subequal in length to pereonite 3.