Cymadusa elegantis Peart, 2007, sp. nov.
Creators: name: Peart, Rachael A.
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Ampithoidae
Cymadusa
Cymadusa elegantis

description: Cymadusa elegantis sp. nov.
(Figs. 4–7)
Cymadusa sp. 1.— Edgar, 1983: 129 –157.
Type material. Holotype: female, ovigerous, 13.0 mm, AM P51255, Fancy Point, Bruny Island, Tasmania, Australia, 43°13’S 147°21’E, 4 January 1979, 2 m, on Sargassum sp., G. Edgar.
Paratypes: AM P51256 (male, 14.0 mm), AM P51257 (16 females and males, 5–12 mm), type locality.
Diagnosis. Antenna 1 accessory flagellum with 1 article. Maxilla 1 inner plate with 5 slender setae. Gnathopod 1 without densely setose margins; merus produced to form a long, acute distoventral lobe; carpus longer than propodus; palm acute, convex, without midmedial tooth, without posterodistal tooth, with a defining robust seta. Gnathopod 2 with sparsely setose margins; merus produced to form a short, acute distoventral lobe; carpus shorter than propodus; palm acute, entire, without midmedial tooth, with a small subacute posterodistal tooth defining the palm; without defining robust seta; dactylus subequal in length to palm, tapering evenly to an acute point. Epimeron 3 posterodistal corner narrowly rounded. Uropod 3 peduncle with 6 distal robust setae; outer ramus with patch of small conical lateral denticles, with a lateral setal fringe. Telson distally subacute, apical cusps small, with/out oblique lateral and medial rows of slender setae.
Description. Male (based on paratype male, 14.0 mm, AM P51256). Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2 (0.9 x), article 2 longer than article 3 (3.6 x), article 3 shorter than article 1 (0.3 x); accessory flagellum with 1 article (scale-like). Antenna 2 slen- der, similar to antenna 1, not densely setose on ventral margin; peduncular article 4 longer than article 5; flagellum with 29 articles. Mandible molar with 6 robust setae in accessory setal row; palp stout, long, setose along posterior margin, article 1 shorter than article 2 (0.3 x), article 2 subequal to article 3, article 3 longer than article 1 (3 x). Upper lip distally setose, lateral margins each with midlateral notch. Lower lip with lateral lobe longer than medial lobe; mandibular lobe with curved margins, rounded apically. Maxilla 1 palp with 2 articles, with apical robust setae. Maxilla 2: inner plate narrow, outer plate broader. Maxilliped outer plate with large robust setae.
Pereon. Gnathopod 1 with sparsely setose margins; coxa larger than gnathopod 2 coxa; with 2 slender simple setae on the posteroventral corner; produced anteroventrally, anteroventral margin rounded, anterior margin concave; basis subequal in length to coxa, with sparse slender setae, posterodistal lobe absent; merus anterior margin with setae absent; carpus longer than merus, subtriangular, carpal lobe subacute, anterior margin with setae absent; propodus narrow (length 1.9 x width), palm convex, without midmedial tooth, without posterodistal tooth defining palm; dactylus overreaching length of palm, inner margin rugose. Gnathopod 2 coxa without setal fringe; basis subequal in length to coxa, with sparse slender setae, posterodistal lobe large and subacute, with 1 slender seta; merus anterior margin without setae; carpus subtriangular, anterior margin with sparse small, slender setae; propodus broad (length 1.1 x width), not produced into an anterodistally setose lobe. Pereopod 5 basis with marginal robust setae, with medial slender setae; merus subrectangular; distal articles slender; propodus slightly expanded distally, with 3 distal simple, striated, robust setae; dactylus strongly curved. Pereopod 6 basis posterior margin rounded proximally, straight distally, with marginal robust setae, with medial slender setae; merus rectangular; propodus slightly expanded distally, with 3 distal simple, striated, robust setae; dactylus slightly curved. Pereopod 7 basis with marginal robust setae, without medial slender setae; propodus defined by 2 simple, striated, robust setae.
Pleon. Uropod 1 peduncle with 8 robust setae, with long setal fringe; inner ramus slightly longer than outer ramus, with 8 marginal robust setae, slender setae absent; outer ramus with 11 marginal robust setae, slender setae absent. Uropod 2 peduncle with 5 robust setae, setal fringe absent; inner ramus slightly longer than outer ramus, with 9 marginal robust setae, slender setae absent; outer ramus with 9 marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (1.4 x), short with respect to rami length (1.8 x), marginal robust setae present, marginal slender setae absent, with 4 distal slender setae; outer ramus shorter than inner ramus with patch of small conical spines; inner ramus with 4 distal robust setae, with 7 distal slen- der setae.
Female (sexually dimorphic characters; based on holotype female, 13.0 mm, AM P51255). Gnathopod 1 subequal in size to gnathopod 2; coxa smaller than gnathopod 2 coxa, anteroventral margin produced with a small subacute tooth; carpus longer than propodus; propodus narrow (length 1.9 x width); palm acute, entire; dactylus subequal in length to palm. Gnathopod 2 propodus broad (length 1.4 x width); dactylus subequal in length to palm.
Etymology. This species name is derived from the Latin, elegans, fine, select, owing to the extremely long antennae, giving the animal an elegant appearance.
Remarks. Cymadusa elegantis sp. nov. is highly recognisable by its extraordinarily long antenna 1, being longer than the body. The male gnathopod 2 is comparatively larger than on the female but does not possess a midmedial tooth like that of C. imbroglio Rabindranath, 1972.
Cymadusa elegantis is similar to C. grossimana Ledoyer (1984) from New Caledonian, sharing an enlarged gnathopod 2. However, the two species can be distinguished by the length of the antennae (longer in C. elegantis than in C. grossimana), the shape of gnathopod 2 palm (excavate in C. grossimana, entire in C. elegantis), and the shape and size of gnathopod 1. Epimeron 3 of C. grossimana has a small acute posteroventral tooth whereas C. elegantis has a narrowly rounded posteroventral rounded corner.
Habitat. Collected from Sargassum sp. at 2 metres depth.
Distribution. Fancy Point, Tasmania, south east coast of Australia (Tasman Sea).
description: Published as part of Peart, Rachael A., 2007, A review of Australian Cymadusa (Crustacea: Amphipoda: Ampithoidae) with descriptions of eight new species, pp. 1-53 in Zootaxa 1540 on pages 8-13, DOI: 10.5281/zenodo.177791