Caprella tamboensis, Takeuchi & Nagano & Keable, 2022

Takeuchi, Ichiro, Nagano, Kohsei & Keable, Stephen J., 2022, A New Species of Caprella (Crustacea: Amphipoda: Caprellidae) from Gippsland Lakes, Australia, with a Redescription of Caprella acanthogaster Mayer, 1890 from Northern Japan, Records of the Australian Museum (Rec. Aust. Mus.) 74 (1), pp. 1-12 : 6-10

Caprella tamboensis sp. nov.

Figs 5–7

urn:lsid:zoobank.org:act:BACB80DD-D29D-4DC8-89DF-668183E1BFA7

Caprella acanthogaster .— Guerra-García & Takeuchi, 2004: 996–1103, figs 21–26.

Holotype, male, AM P.102618, 01 Dec 2018, 37.85°S 147.81°E, Tambo Bay , Lake King, Gippsland Lakes, Victoria, Australia, coll. M. Jenkins. Paratypes (all same collection details as holotype), 1 male, AM P.102619; mature female (described), AM P.102620; 1 male and 1 mature female, AM P.102621; 2 mature females, AM P.102622; 5 mature females, AM P.102623; ca. 10 individuals, AM P.102624; male, AM P.105616; male, AM P.105617.

Other material. Many, AM P.102617 (same collection details as holotype); 5 males, 5 females, MV J74951 (same collection details as holotype) .

Additional comparative material, all cited by GuerraGarcía & Takeuchi (2004). 3 males, 1 female, P.48785, 3 Jun 1993, 42°42'S 148°E, Mercury Passage, Tasmania, Australia, Coll. G. Edgar. Series from 29 Mar 1996, 42°34'S 148°5'E, “Scallop aquaculture”, Mercury Passage, Tasmania, Australia, coll. G. Edgar and N. Barrett, substrate Undaria pinnatifida , 5 m depth – many specimens, P.48790; many specimens P.48791 ; 1 male with 2 microscope slides P.61248 (ex P.48790); 1 female P.61249 (ex P.48791).

Description

Male, holotype, AM P.102618, body length, 21.93 mm. Head, 1.25 mm; pereonite 1, 3.92 mm; pereonite 2, 5.14 mm; pereonite 3, 3.35 mm; pereonite 4, 3.02 mm; pereonite 5, 3.25 mm; pereonite 6, 1.01 mm; Pereonite 7, 0.98 mm, respectively. Pereonite 2 longest.

Head and pereonites elongate; eye large, distinctive. Pereonite 2 with small anterolateral projection, lateral posterior projection, and 3 paired mid-dorsal to posterodorsal projections. Pereonites 3–4 each with ca. 5 lateral and numerous dorsal projections. Pereonite 5 with small anterolateral projection and numerous dorsal projections. Pereonites 6–7 each with paired mid-dorsal projections.

Mouthparts, similar to those described in the current study for Caprella acanthogaster .

Antenna 1 elongate, 0.7 × body length; peduncle article 2 longest, peduncle article 3 0.90 × peduncle article 2 length; flagellum 0.45 × peduncular length, with 19 articles, proximal article composed of 3 partially fused articles. Antenna 2 slender, 0.35 × antenna 1 length; peduncle article 2 to flagellum article 1 with dense plumose setae (swimming setae).

Gnathopod 1 slender, setose on carpus to propodus. Gnathopod 2 begins 0.20 along posterior margin of corresponding pereonite; coxa vestigial; basis 1.0 × length of pereonite 2, with projection near distal margin; propodus ovate, large, length 2.5 × width, with three rows of setae on dorsal margin; palm proximal projection with 1 robust (grasping) seta; palm margin wide, slightly convex, with small triangular midpalmar projection, shallow sinus, and shallow distal shelf. Gill 3 elongated, length 1.1 × corresponding pereonite. Gill 4 elongated, length1.0 × corresponding pereonite length.

Pereopod 5 slender; basis shorter than propodus; carpus with ca. 10 setae on anterior margin; propodus with 1 pair of robust setae proximally 0.3 palm length from articulation with carpus and 13 setae along palm; dactylus curved. Pereopod 6 longer than pereopod 5. Pereopod 7 longer than pereopod 6.

Penis elongated. Uropod 1 peduncle short; ramus round (length 1.4 × width) with 5 lateral setae. Uropod 2 vestigial with 7 setae at basal part.

Mature female, AM P.102620, body length, 9.40 mm. Head, 0.67 mm; pereonite 1, 0.46 mm; pereonite 2, 1.80 mm; pereonite 3, 1.66 mm; pereonite 4, 1.58 mm; pereonite 5, 1.80 mm; pereonite 6, 0.77 mm; Pereonite 7, 0.66 mm, respectively. Pereonites 2 and 5 longest.

Head round. Pereonite 1 with paired posterodorsal projections. Pereonites 2–5 each with numerous lateral and dorsal projections. Pereonites 6–7 each with 2 paired dorsal projections.

Antenna 1 elongate, 0.70 × body length; peduncle article 2 longest; flagellum subequal to peduncular length, with 17 articles, proximal article composed of 2 partially fused articles. Antenna 2 slender; 0.60 × antenna 1 length. Gnathopod 2 inserted 0.25 along posterior margin of corresponding pereonite; basis 0.60 × length of pereonite 2, propodus oval. Gills 3–4 slender, length ca. 0.9 × corresponding pereonite length.

Distribution ( Fig. 4 ).

Type locality. Tambo Bay, Lake King, Gippsland Lakes, Victoria, Australia.

Other locality. Mercury Passage, Tasmania, Australia (Guerra-García & Takeuchi, 2004).

Etymology. The species name refers to the type locality of the species Tambo Bay, Gippsland Lakes, Victoria.

Remarks

The highly dense aggregations of Caprella attached to fisheries nets at Tambo Bay, Gippsland Lakes, Victoria, were first discovered by M. Jenkins, a local fisherman ( Fig. 8 ), and the specimens were sent to the Australian Museum for identification.

While the body length of the male specimen of the C. acanthogaster redescribed here from Japan is double that of the Caprella from Gippsland Lakes the former has less articles in the flagellum of the antenna 1. The number of antenna 1 flagellar articles has been reported to increase in Caprella danilevskii Czerniavski, 1868 by one or two in every moult as individuals mature ( Takeuchi & Hirano, 1991). Taking this into account it appears both male specimens described here from Japan and Gippsland Lakes are at approximately the same stage of development. Therefore, comparison of Caprella from Gippsland Lakes and C. acanthogaster s.str. from Far East Asia ( Marelli, 1981; present study) based on large mature males has revealed that they are similar but the former differs in: i) the small midprojection on the palm of propodus of gnathopod 2; ii) the relatively longer antenna 1 peduncle article 2, being longer than article 3; and iii) the relatively higher number of articles in the antenna 1 flagellum. To accommodate these specimens, we establish a new species, Caprella tamboensis sp. nov. The specimens of C. acanthogaster reported form Mercury Passage, Tasmania, Australia, by Guerra-García & Takeuchi (2004) are also identified as belonging to this new species.

The male specimen reported by Mayer (1890) as C. acanthogaster found in the collection from the Museum Godeffroy, Hamburg, Germany, possibly originated from Australia (see remarks under C. acanthogaster above). The Museum Godeffroy was founded by Mr Cesar Godeffroy, one of the merchant magnates of Hamburg, Germany, whose ships had sailed around every ocean for over half a century (Ward, 1876). Included in these travels were expeditions concentrated around the South Sea Islands to collect crustaceans, molluscs, starfish, sea urchins, holothurians, corals, sponges, sea fans, and other organisms (Ward, 1876). Ward (1876) noted that Mr Darnel (probably staff of Mr Cesar Godeffroy), while working in EasternAustralia, passed through Queensland and penetrated three hundred miles into the interior, obtaining strange forms of molluscs and fishes. Therefore, there is a possibility that the specimen of Caprella in the Museum Godeffroy collection cited by Mayer (1890) was obtained in Australia and may be C. tamboensis or another species related to C. acanthogaster or C. tamboensis . However, with the closure of the Museum Godeffroy in 1885 the collection was scattered among various institutions (Wikipedia, 2021) and we have been unable to locate the specimen to resolve this.

Evidence provided here suggests a different conclusion to that of Guerra-García & Takeuchi (2004) who reasoned that Caprella acanthogaster s.l. (= C. tamboensis sp. nov.) from Tasmania was possibly introduced from Far East Asia as the specimens were found among a scallop aquaculture facility, including on the invasive alien macro-alga Undaria pinnatifida (Harvey) Suringar, 1873 , and suggested the likely transport vector as associated with spat of scallop from the north-eastern Pacific (Edgar, 2000; Guerra-García & Takeuchi, 2004). While we do not discount the possibility that the caprellid recognized here from Gippsland Lakes and Tasmania as C. tamboensis may have been introduced to those areas we do not find it to be the same species as C. acanthogaster and it is equally likely it may be a native species, widely distributed but as yet largely unrecorded in southern Australia. For example, Guerra-García et al. (2020) have noted examination of the Caprellidae from South Australia and Victoria would also assist in filling gaps in understanding the biodiversity and biogeographical patterns of the Australian fauna.

Our observations also highlight that further detailed morphological study, possibly combined with genetic analysis, may be necessary for reconstructing the phylogeny and to better understand the distribution pattern for species reported as C. acanthogaster and other similar related species from the temperate to cold waters of the northeast Asia. These include C. mutica and C. eximia , both of which were reported to be closely related to C. acanthogaster (Vassilenko, 1993) , as well as C. centroda Vassilenko, 1993 from the Chishima Islands (Kurile Islands) located between Hokkaido and the Kamchatka Peninsula.

ACKNOWLEDGEMENTS. The authors express their gratitude to Mr M. Jenkins, who discovered the aggregations of the new species of Caprella described in this study and donated them to the Australian Museum, and to Ms H. Stoddart for her kind arrangements related to our research on Caprella .

Figures

Figure 4. Distribution of Caprella acanthogaster Mayer, 1890 and related species.Data is based on Mayer (1890), Schruin (1937), Utinomi (1943a,b), Arimoto (1976), Vassilenko (1974), Wang et al. (1989), Lee & Lee (1993), Hosono & Munehara (2001), Guerra-García & Takeuchi (2004), Takeuchi (2005), Lee & Hong (2009, 2011), Cao et al. (2013), Wei et al. (2016), Heo et al. (2020), and the present study.

Figure 5. Caprella tamboensis sp. nov. fromTambo Bay, Lake King, Gippsland Lakes,Victoria,Australia.Holotype, male,AM P.102618, 21.93 mm. Paratype, female, AM P.102620, 9.40 mm. Bar indicates 1.0 mm.

Figure 6. Caprella tamboensis sp. nov.from Tambo Bay, Lake King, Gippsland Lakes, Victoria,Australia.Holotype, male,AM P.102618, 21.93 mm. Bar indicates 1.0 mm, except for 0.1 mm to AB.

Figure 7. Caprella tamboensis sp.nov.from Tambo Bay, Lake King, Gippsland Lakes, Victoria,Australia. Holotype, male,AM P.102618, 21.93 mm. Bar indicates 0.1 mm.

Figure 8. Aggregation of Caprella tamboensis sp. nov.on a fishing net inTambo Bay, Lake King, GippslandLakes, Victoria,Australia. The image was taken from a screen shot of the video recorded by Mr M. Jenkins when the specimens reported here were collected.