Caprella sarahae, Peart & Woods, 2025

Caprella sarahae sp. nov.

( Figs. 1 View FIGURE 1 , 12–14 View FIGURE 12 View FIGURE 13 View FIGURE 14 )

Type material. Holotype: NIWA 155331 View Materials , male (13 mm), SA-3543, stn Z18756, Hoho Islet , Snares Islands / Tini Heke, New Zealand, 48°7.002’S 166°36’E, 0–1 m, amongst turf of hydroids in rock crevices in lower Durvillea sp. zone, coll. G.D. Fenwick, 17/02/1977 GoogleMaps . Paratypes: NIWA 155332 View Materials , female (7 mm), SA-3543, Hoho Islet , Snares Islands / Tini Heke, New Zealand, 48°7.002’S 166°36’E, 0–1 m, amongst turf of hydroids in rock crevices in lower Durvillea sp. zone, coll. G.D. Fenwick, 17/02/1977 GoogleMaps . Paratypes: NIWA 155333 View Materials , approximately 200 specimens (males, females and juveniles, 3–13 mm), SA-3543, Hoho Islet , Snares Islands / Tini Heke, New Zealand, 48°7.002’S 166°36’E, 0–1 m, coll. G.D. Fenwick, 17/02/1977 GoogleMaps .

Other material examined. NIWA 155334 View Materials , approximately 150 specimens (males, females and juveniles, 4–13 mm), SA-3544, stn Z18757, Hoho Islet , Snares Islands / Tini Heke, New Zealand, 48°7.002’S 166°36’E, 0–1m, under rocks and among hydroids in rock pool, lower Durvillea sp. zone, coll. G.D. Fenwick, 17/02/1977 GoogleMaps .

Type locality. Hoho Islet , Snares Islands / Tini Heke, New Zealand, 48°7.002’S 166°36’E GoogleMaps .

Etymology. The species is named for Sarah Allen of NIWA who has sent the first author (RP) numerous specimens of Caprella to identify through MITS (Marine Invasives Taxonomic Service), leading primarily to this paper.

Diagnosis. Head rectangular, with slight, rounded projection; body smooth and robust. Antenna 1 over ½ of body (0.71 ×); peduncular articles 1–2 robust and expanded in male and slender in female, sparsely setose, longer than flagellum (3.9 ×). Antenna 2 reaching to ½ length of article 2 of peduncle of antenna 1, bearing long setae on ventral margin. Pereonite 1 and 2 comprising half body length. Gnathopod 1 robust, with palmar margin of propodus setose with pair of proximal grasping spines on rounded tooth; palm straight; dactylus smooth. Gnathopod 2 in male arising at distal third of pereonite 2; basis approximately ½ length of propodus and one-third length of pereonite 2; palmar region of propodus straight, weakly setose with posterior corner truncated bearing short robust seta, two teeth predactylar; dactylus strong, apex pointed and unconstricted with distal end smooth, inner margin slightly sinuous. Gnathopod 2 in female inserted at anterior one-third of pereonite 2; palm of propodus slightly sinuous. Pereonite 2 with acute ventral projection between insertion of gnathopods 2. Gills short and oval in both sexes. Pereopods 5–7 of similar lengths; palmar margin of propodus concave lined with short dense robust setae with two combed grasping spines and slightly expanded posterior corner.

Description. (Based on holotype male, 9.5 mm). Body: Head anterodistal margin rectangular, male slightly produced forward. Head fused with pereonite 1, suture present and visible. Pereonite smooth, no dorsal projections; pereonite 2 with lateral, anterior angled projection over gnathopod 2 insertion, all other pereonites without lateral projections. Ratio of lengths pereonites 1 (not including head) 1: 1.9: 1: 1: 0.7: 0.6: 0.6.

Head: Antenna 1 0.71 × body; peduncular article 2 longest, 1.9 × article 1, 1.5 × article 3; flagellum 0.3 × peduncular length with 15 articles. Antenna 2 0.5 × antenna 1 length; peduncular article 4 subequal in length to article 5.

Mouthparts: lower lip, inner lobe round. Mandible right incisor with five teeth, lacinia mobilis with seven teeth followed by three plumose setae, molar distinct. Mandible left incisor with four teeth, lacinia mobilis with two toothed teeth followed by three plumose setae, molar distinct. Maxilla 1 outer plate with seven stout apical setal-teeth; palp two-articulate; article 2 4.1 × article 1 with 14 apical robust setae and single line of medial slender setae. Maxilla 2 inner plate, oval, with ca. 23 marginal and apical slender setae; outer plate with ca. 14 mainly apical slender setae, inner plate shorter than outer plate. Maxilliped inner plate with two stout setae on inner corner of distal margin, with line of setae on entire distal margin; outer plate 2.0 × inner plate with ca. 10 robust setae on inner margin, slender setae apically; palp four-articulate, article 2 longest, setose along entire inner margin, inner margin concave; dactylus inserted subapically, therefore producing setose lobe/hood apically, setose along length medially, acute tip.

Gnathopod 1 basis subequal to ischium, merus, carpus combined; carpus subtriangular, densely setose on posterior lobe; propodus subovate, length 1.2 × width, setae along anterior margin; palm beginning at posterior margin; proximal projection equipped with pair of robust setae (grasping spines) followed by ca. 32 setae along palm; dactylus weakly curved, smooth inner margin. Gnathopod 2 basis anterior margin serrate, produced to form triangular flange; ischium 0.3 × basis, with anterior distal triangular lobe; propodus longer than wide (length 2.4 × width); palm beginning ⅓ along posterior margin, proximal projection with single small robust seta (grasping spine) followed by three slender setae; palm with double triangular projection prepalmar, row of small setae along palm. Gill 3 length 0.7 × pereonite 3; gill 4 subequal to gill 3. Pereopod 5 basis 0.6 × propodus, posterior margin serrated and expanded distally to form subacute flange; ischium 0.3 × basis; merus 0.75 × basis expanded posteriorly to form rounded lobe; carpus 0.95 × basis, anterior margin lined with robust plumose setae; propodus longest, with paired combed robust setae 0.3 along posterior margin on rounded corner, palm lined with 19 plumose robust setae; propodus posterior margin lined with setae distally; length propodus 1.6 × width; dactylus short, strongly curved. Pereopod 6 subequal in length to pereopod 5, similar structure to P5; length propodus 1.7 × width. Pereopod 7 slightly shorter than pereopod 6 (0.9 × shorter); propodus posterior margin lined on distal half with robust setae; length propodus 1.8 × width.

Paratype mature female, NIWA 155332, 7 mm. Ratio of pereonites 1–7 (not including head) 1: 3.8: 3.7: 2.6: 3: 1.9: 1.6. Antennae 1 approximately ½ body length. Antenna 1 slender; peduncle article 2 longest, 1.5 × article 1, 1.55 × article 3; articles 1 and 3 subequal; flagellum 14 articles, shorter than peduncle (0.7 ×). Antenna 2 reaching to length of peduncle. Gnathopod 1 basis shorter than ischium, merus, carpus combined; carpus subtriangular, densely setose on cup-shaped posterior lobe; propodus subtriangular, length 1.6 × width, setae along anterior margin; palm beginning at posterior margin; proximal projection equipped with pair of combed robust setae followed by ca. 17 setae along slightly serrate palm; dactylus weakly curved, serrate inner margin. Gnathopod 2 basis anterior margin serrate, produced to form triangular flange; ischium 0.15 × basis, without lobe; propodus longer than wide (length 2 × width); palm beginning ⅓ along posterior margin, proximal projection with single small robust seta followed by 1 slender seta; palm with subrectangular subquadrate projection prepalmar, plus small subacute projection ⅔ along palm, row of robust and slender setae along palm, dactylus inner margin slightly serrate and lined with small setae.

Distribution. New Zealand.

New Zealand biosecurity status. Native.

Remarks. As mentioned above, Caprella equilibra is known as a presumed cosmopolitan species with supposedly very little morphological variation across the globe. McCain (1968) gave a very detailed synonymy. Guerra-Garcia (2003) noted that the specimens examined from the subantarctic islands of New Zealand were almost identical to those examined by Krapp-Schickel (1993) from the Mediterranean Sea. Whether it is truly a cosmopolitan species or an early invader (recorded from New Zealand in the 1870s), or a species complex is difficult to determine at present. There are significant differences between the members of the complex of species ( Table 3) and show that Caprella sarahae sp. nov. is a distinct species.