Comprehensive Description

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“Cerapus fallohideus sp. nov.


Cerapus sp. C Lowry 1974: 123; Fenwick 1976:2 3, 7-8, 16.



Type material. Holotype, male, 4-2mm, NMNZ CRZ2220; allotype, 5-2mm, ovigerous (8 eggs), NMNZ CRZ2221; 2 paratypes, male and female, BMNH 1979: 193: 2; 2 paratypes, male and female, USNM 172410; 105 paratypes AM P27443. Old Wharf, Kaikoura, New Zealand (42 ° 25' S, 173° 42' E). living in a sheltered environment on the green alga Caulerpa brownii, 4-5 m depth, 25 November 1973, G. D. Fenwick.


Additional material. 217 specimens, AM P27414, AM P27416-17, AM P27440-42, AM P27444 46, Old Wharf, Kaikoura, New Zealand, living in a sheltered environment on the green alga C. brownii, 3-7 m, 25-26 November 1973, G. D. Fenwick. 18 specimens, AM P27448-49, Fii~h Bay, Kaikoura, New Zealand, living in a sheltered environment on the green alga C. brownii and in a sponge, 7-12 m, 22 December 1973, 26 January 1974, D. S. Horning and J. K. Lowry. 4 specimens, AM P27450, Seal Reef, Kaikoura, New Zealand, living in a sheltered environment on the green alga C. brownii. 2-5m, l0 August 1974, D. S. Horning.


Diagnosis. Antenna 1 long, thin; peduncular article 1 produced distally over


article 2, flagellum 5-articulate. Female gnathopod 2 subchelate, palm oblique with


strong proximal spines. Telson cleft about 75% of its length.


Description. Male: head with short acute rostrum, eyes in lateral cephalic lobes. Body long, thin, cylindrical, urosomites dorsoventrally flattened; coxae small, not contiguous, wider than deep. Colour in life: rostrum and anterior quarter of head


white, bordered posteriorly by a red band, posterior quarter pink; posterior half of head mottled, brownish-red; eyes black concavities on white; peraeonites 1 to 5 mottled white with light red bars marking anterior margins; posterior peraeonites


and pleonites translucent; antenna l, peduncular article 1 white with a red dorsal flange distally, articles 2 and 3 rimmed in red with a bright yellow granular strip though centre, flagellum olive with small patch of yellow on each article; antenna 2,


peduncle translucent with patches of white pigment, except article 5 which is bright yellow, flagellum translucent olive; mouthparts and gnathopods light red; paraeopods translucent. Eggs in the female translucent, embryos bright orange-red.


Antenna 1 setose, long, thin, subequal to antenna 2; peduncle, article 1 produced distally about 0"3 times as long as article 2, operculate; article 3 as long as unprodueed portion of article 1, 3 times as long as broad; flagellum well-developed, 5-articulate. Antenna 2 setose, long, thin; gland cone produced; peduncular articles 4 and 5 subequal; flagellum 6-articulate.


Mandible triturating molar; right mandible, incisor with 5 teeth; no lacinia mobilis; 3 accessory blades; molar flake and molar seta present; palp long, 3- articulate, articles 2 and 3 subequal, with long slender setae medially, left mandible the same, except incisor with 4 teeth, lacinia mobilis present. Maxilla 1 inner plate small, a small seta distally; outer plate with 10 terminal spines; palp 2-articulate with oblique row of 3 subdistal setae and 5 terminal spines. Maxilla 2 outer plate slightly longer than inner, with terminal seta; inner plate with 9 plumose medial setae and a row of terminal setae. Maxilliped inner plate subquadrate with 2 short, stout spines along distal margin and a subdistal spine: outer plate ovate with 6 stout medial to distal spines and 2 distal setae: palp 4-articulate, article 3 with strong mediodistal spine row, article 4 with strong terminal spine.


Gnathopod 1 subchelate; article 5 lobate; article 6 longer than broad, palm oblique with 4 strong proximal spines, surface of palm lined with very short spines; dactyl reaching end of palm, closing margin with row of very small spines. Gnathopod 2 carpochelate; anterior margin of article 2 lined with setae, weakly crenulate; article 5 enlarged, 1"25 times as long as broad, palmar margin with a large bordering tooth and slightly smaller middle tooth; article 6, 2-2 times as long as broad: dactyl sparsely setose on posterior margin.


Peraeopods 3 and 4 article 2 large, 1"7 times as long as broad; article 6, 2-5 times as long as broad. Peraeopod 5 very similar to peraeopod 5 of C. stoorus except setae on article 5 are plumose. Peraepods 6 and 7 thin, sparsely setose distally; dactyl triuncinate on peraeopod 6 and biuncinate on peraeopod 7.


Urosomites separate. Uropod 1 biramous, peduncle 2-5 times as long as broad with a lateral row of spines, distal margin a fan of small spines; outer ramus 0-8 times as long as peduncle, lateral margin with smM1 short spines and longer setae, a terminal spine partially surrounded by collar of small spines; inner ramus half as long as outer ramus, a collar with a distal fan of short spines partially surrounding large terminal spine. Uropod 2 uniramous, extending nearly halfway along inner ramus of uropod 1; peduncle nearly 2-5 times as long as ramus; ramus with small patch of short lateral spines and a large subterminal plumose seta. Uropod 3 uniramous, peduncle twice as long as broad; ramus very small, biuncinate. Telson broader than tong, cleft about 75% of its length; 10 12 recurred spines on surface of each lobe, a small seta at corner of each lobe.


Female same as male except gnathopod 2, article 5 not greatly enlarged, subchelate; slightly longer than broad, posteriorly lobate with a row of setae; article 6, 1-6 times as long as broad, palm oblique with 5 proximal spines and a row of very small spines lining border; dactyl with small spines along posterior border.


Tube. The tube of C. fallohideus is cylindrical and not as strong as the tubes of C. harfootus or C. stoorus. It can be lightly stuck to any surface by the animal, and is covered with quartz grains, foraminiferan tests and calcareous grains. Some tubes are very long, up to 15 ram.


Etymology. C. fallohideus is named for the tall, slim breed of fair-skinned hobbits


who lived in the forest and were the least numerous, but most distinctive of the three




Remarks. From a diving collection made in about 7 m depth at Fifth Bay,


Kaikoura on 27 January 1974, 175 C. fallohideus, 3 C. stoorus and 1 C. harfootus were found living on Caulerpa brownii. C. fallohideus was observed alive in the laboratory and many were found to be without tubes, some were living in polychaete tubes and one ovigerous female was living in a tube in a sponge. They can turn in their tubes and if dislodged re-enter tail first. When crawling over objects, although their peraeopods may come out of the tube they are hardly used, and movements are carried out mainly by using gnathopods 1 and 2. They were also observed 'feeding' on detritus which they manipulate in their gnathopods and maxillipeds.


Fenwick (1976) collected C. fallohideus living on C. brownii in the sheltered area of Old Wharf, Kaikoura. It was about the fourth most abundant amphipod in this habitat, but was very rare in exposed environments such as St. Kilda Rocks. Fenwick (1976) believed that they were only found in sheltered environments where shell fragments used in tube construction were common, and this ties in well with their distribution in Fifth Bay where C. brownii grows in patchy meadows on a coarse sand bottom.


Distribution. Kaikoura, New Zealand (type locality), 3-7 m.”



(Lowry, 1981: 192-198)


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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