Caprella mutica Schurin, 1935

Peart, Rachael A. & Woods, Chris, 2025, Caprellidae (Crustacea: Amphipoda) of Aotearoa New Zealand waters: a constantly changing landscape, Zootaxa 5568 (1), pp. 1-65 : 12-14

Caprella mutica Schurin, 1935

( Fig. 1 , 4–5 )

Caprella mutica Schurin, 1935: 198–199 , fig. 1; 1937: 27–28, fig. 7–8.— Utinomi, 1947: 75.— Utinomi, 1964: 14, fig. 1.— Vassilenko, 1974: 201, figs. 118–119.— Arimoto, 1976: 111, fig. 59.— Willis et al. 2004: 1027–1028, fig. 1.— Faasse, 2005: 22, figs. 1–3.— Willis et al. 2009: 249–259.—Turcotte & Sainte-Marie, 2009: 1, fig. 1.— Boos et al., 2011: 129–156.— Peters & Robinson, 2017: 61–66.— Daneliya & Laakkonen, 2012: 1, figs. 2–3.—Webber et al., 2010: 156, 219.— Schnabel et al., 2023: 436.

Type locality. Peter the Great Bay , Siberian coast of the Sea of Japan .

Material examined. NIWA 155320 ( MITS 75069), many males and females, Lyttelton Harbour/Whakaraupō, LYT-29241- AM, 07/2019.

Diagnosis. Head rounded, without projection; body covered in angular projections and setae, pereonites are robust.Antenna 1 over half of body (0.6 ×); peduncular articles 1–2 expanded, robust and densely setose in males and slender and, sparsely setose in females,—longer than the flagellum (males) and slightly shorter than the flagellum in females. Antenna 2 reaching to ½ length of article 2 of peduncle of antenna 1, bearing long dense setae on ventral margin (male). Antenna 2 reaching beyond antenna 1 peduncle, bearing long setae on ventral margin (female). Gnathopod 1 small but robust, with palmar margin of propodus setose with pair of proximal grasping spines; palm somewhat straight; dactylus serrate. Gnathopod 2 arising at distal ⅓ of pereonite 2 (male); basis approximately the length of propodus and ⅔ length of pereonite 2 (male); palmar region of propodus sinuous, setose with posterior corner blunt bearing robust setae, large acute tooth predactylar and secondary tooth of same length just posterior to predactylar tooth with excavation in between; dactylus strong, apex pointed and unconstricted with distal end smooth. Gnathopod 2 in female inserted just anteriorly of midpoint on pereonite 2; palm of propodus slightly convex. Gills long and slender in both sexes. Pereopods 5–7 increasing in length posteriorly; palmar margin of propodus straight bearing short dense setae with two median grasping spines and expanded posterior corner.

Distribution. South Island/Te Waipounamu; lower North Island/Te Ika-a-Māui, New Zealand ( Table 1). Also extensively found in Europe, North America, South Africa and Japan.

New Zealand biosecurity status. Adventive, but well established in New Zealand.

Remarks. Although similar morphological variations are present in males of overseas forms of C. mutica , this species is quite distinctive amongst New Zealand caprellids. The males have dense spiny projections covering pereonites 3–7, densest on pereonites 3–5. Pereonites 1–2 are covered in thick long setae extending along the first antennae, reaching all over the second gnathopods but absent on the first gnathopods. The females have reduced spination over the body, and very little setation. The males have articles 1–3 of antenna 1 enlarged, and pereonites 1–2 (when pereonite 1 combined with the head) of subequal length.

Caprella mutica is native to north-east Asia (Peter the Great Bay, Vladivostok) and has a complex history of global invasion. This species is especially prevalent in temperate northern hemisphere waters (including Europe, North America and Asia) and has an isolated occurrence in the Southern Hemisphere from New Zealand waters ( Boos et al. 2011), and southern Africa ( Peters & Robinson 2017). Detailed studies of similar climates and conditions around Australia, and southern America do not record this species ( Thiel et al. 2003; Guerra-García & Takeuchi 2004). Introduced populations of this species are associated with artificial environments including shipping, marinas and aquaculture facilities, but in its native environment are associated with macroalgae and aquaculture structures ( Boos et al. 2011).

Caprella mutica was first recorded from New Zealand in 2002 but documented officially in 2008 ( Woods et al. 2008; Ahyong & Wilkens 2011). First noted from in the southern Port of Timaru in 2002 as part of a national baseline biota survey of ports and marinas ( Inglis et al. 2006), the distribution is now considered to be in most major ports on the South Island/Te Waipounamu, with a vessel biofouling record for Wellington New Zealand ( Fig. 1 ) ( Willis et al. 2009) ( Table 1). This distributional record, though quite extensive, is primarily restricted to major ports and areas of aquaculture activities but not to smaller centers largely due to the sampling effort of the long-running (since 2002) targeted surveillance programme for non-indigenous species in 12 ports and marinas around New Zealand (National Marine High Risk Site Surveillance (NMHRSS) programme) undertaken for the Ministry for Primary Industries (MPI, Biosecurity New Zealand). This indicates that the species could potentially be more widespread than these records suggest. The known distribution for C. mutica in New Zealand is synanthropic and associated with maritime vessels and associated infrastructure, and aquaculture operations such as finfish and mussel farms ( Fig. 5 ) (Woods, unpublished data) ( Table 1).

substratum type are provided. Population abundances (number of caprellids per m 2) measured at the time of detection are also provided (where recorded) along with source.

Figures

FIGURE 1. Distribution of caprellid species in the New Zealand Exclusive Economic Zone (map: E. Leunissen, NIWA).

FIGURE 4. Caprella mutica Schurin, 1935, Lyttelton Harbour/Whakaraupō, New Zealand. A, male, NIWA 155320, 24.5 mm; B, female, NIWA 155320, 10.5 mm.

FIGURE 5. Caprella mutica Schurin, 1935, in situ, showing different fouling situations: finfish farm netting (top left); mussel farm backbone rope (top right); marina pontoon (bottom left); and vessel hull (bottom right) (images: C. Woods, NIWA).