Cymadusa setosa
Creators: name: Peart, R. A.
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Ampithoidae
Cymadusa
Cymadusa setosa

description: Cymadusa setosa (Haswell, 1879)   
(figures 16–19)  
 Ampithoe setosa Haswell, 1879: 338.   
 Grubia setosa: Stebbing, 1906: 644.   
 Grubia compta: Pearse, 1912: 376, figure 6.   
 Amphithoides compta: Stebbing, 1906: 645.   
 Cymadusa compta: Bousfield, 1973: 182–183, pl. LV.2; Nelson, 1980 (ecology).   
 Grubia filosa: Schellenberg, 1928: 666, figure 206; K. H. Barnard, 1937: 171–172; Shoemaker, 1935: 245–249, figures 4, 5.   
 Cymadusa filosa: J. L. Barnard, 1955: 29–30, figure 15 (with references); J.L. Barnard, 1965: 3 (key); Rabindranath, 1972: 173–175, figures 8, 9; Griffiths, 1973: 277–278; Griffiths, 1974a: 225; Griffiths, 1974b: 274; Griffiths, 1975: 106; Griffiths, 1976: 25 (key); Ledoyer, 1984: 15–18, figures 5, 6 (Group II setose).   
 Type locality. Kurnell, Botany Bay, New South Wales, Australia.   
 Material examined. AM P10853 (male), on rocky shores between tide marks, Kurnell, Botany Bay, New South Wales, Australia, 27 October 1927, F. A. McNeill and T. Iredale, 10.5 mm. AM P10854 (five females and two males), on rocky shores between tide marks, Kurnell, Botany Bay, New South Wales, Australia, 27 October 1927, F. A. McNeill and T. Iredale.   
 Diagnosis. Antenna 1 with two-articulate accessory flagellum. Antenna 2 peduncle with densely setose margins. Gnathopod 1 poorly setose; merus produced to form a long, acute, anteroventral lobe; carpus long, narrow and subrectangular. Gnathopod 2 with densely setose margins; propodal palm with a defining posterodistal, small, subacute tooth and with a subquadrate mid-palmar tooth; dactylus shorter than palm.   
 Description   
Based on the neotype, male, 10.5 mm length.  
 Head. Antenna 1 subequal to antenna 2; peduncular article 1 subequal to article 2, article 2 longer than article 3, article 3 shorter than article 1; accessory flagellum with two articles. Antenna 2 dense, plumose setae along the margins of the peduncle; peduncular article 4 longer than article 5. Upper lip entire, distal setae present. Lower lip outer plate outer lobe longer than inner lobe. Mandible with nine robust setae in setal row; palp article 1 shorter than article 2, article 2 subequal to article 3, article 3 longer than article 1, setae on posterior margin and apex. Maxilla 1 palp apical margin with robust setae; inner plate with 11 slender setae. Maxilla 2 outer lobe broader than inner lobe. Maxilliped strongly setose.   
 Pereon. Gnathopod 1 more slender but longer than gnathopod 2; poorly setose; coxa produced forward, anterior margin straight, ventral and part of anterior margin with long plumose setal fringe; basis longer than the coxa, without long plumose setal fringe, distal lobe large and subacute; merus produced to form a long, acute anteroventral lobe; carpus longer than merus, longer than propodus, margins parallel at distal end, carpal lobe rounded to straight with distal subacute corner; propodus ovoid; palm entire, straight, posterodistal tooth absent, mid-palmar tooth absent; dactylus longer than palm. Gnathopod 2 margins with long, plumose setae; coxa with long, plumose setal fringe on ventral margin only; basis longer than coxa, with long plumose setae, distal lobe absent; merus produced to form a small, rounded anteroventral lobe; carpus longer than merus, shorter than propodus; propodus subquadrate; palm entire, straight, posterodistal tooth subacute and small, midpalmar tooth present and subquadrate; dactylus shorter than palm, tapering evenly.   
 Pereopods 3 and 4 similar in shape; coxae with a dense, simple setal fringe. Pereopod 5 coxae with setal fringe on ventral margin and without medial setae. Pereopod 6 basis with medial setae. Pereopod 7 basis subrectangular. Pereopods 6 and 7 much longer than pereopods 3–5; distal articles with setae.   
 Pleon. Epimeron 3 with a small subacute tooth. Uropod 1 peduncle with 11 robust setae; outer ramus shorter than inner ramus. Uropod 2 outer ramus shorter than inner ramus. Uropod 3 with seven distal peduncular robust setae; outer ramus shorter than inner ramus, hooks both strongly recurved, setal fringe present on lateral margin; inner ramus with both apical robust and slender setae. Telson truncated, apical slender setae in oblique rows, also with lateral setae, apical cusps present.   
 Female. Based on animal 11 mm length, AM P10854. Animal cream to white in ethanol.   
 Head. Antenna 1 longer than antenna 2; primary flagellum with 66 articles. Antenna 2 weakly setose on ventral margin; peduncular article 4 subequal to article 5.   
 Pereon. Gnathopod 1 subequal to gnathopod 2, slightly more robust than gnathopod 2; coxa ventral margin only with long, plumose setal fringe; basis subequal to the coxa; merus produced to form small subacute anteroventral lobe; carpus margins divergent at distal end, carpal lobe rounded; dactylus subequal to propodal palm. Gnathopod 2 weakly setose; coxa with long plumose setal fringe on posterior twothirds of the ventral margin; basis subequal to coxa, weakly setose; merus produced to form small, rounded anteroventral lobe; propodal palm mid-palmar tooth absent; dactylus subequal to palm.   
 Remarks   
 The original description of this species (Haswell, 1879) is incomplete and the specimen described was not actually illustrated. The collections were examined and no type material was located. One specimen (AM P3416) was located which was labelled as a ‘possible SYNTYPE’ (Springthorpe and Lowry, 1984). However, there is no direct evidence to support that this specimen is one of Haswell’s types. The specimen is also in very poor condition. Ideally to stabilize the name of Cymadusa setosa a neotype should be allocated. However, as the ‘possible syntype’ exists and cannot be disqualified from the type series, the neotype cannot be established. The specimens documented here are selected from specimens collected from the type locality (Botany Bay, NSW) and identified by K. Sheard as Cymadusa setosa (Haswell, 1879). This species is therefore removed from synonymy with Cymadusa filosa. This description is required to distinguish these specimens from other highly setose specimens present in Australian waters, Indo-west Pacific waters and also forms from elsewhere in the world.   
 Cymadusa setosa is most similar morphologically to Cymadusa filosa sensu stricto. These similarities include an elongated gnathopod 1 which has a merus with a long, acute anteroventral lobe. Gnathopod 2 is a similar shape in both species. The differences between the two species include: C. setosa has antenna 1 subequal in length to antenna 2 in the male (whereas C. filosa has antenna 1 longer than antenna 2 in the male); the mandibular palp is strongly setose with three to five setae on article 2 and 20 setae on article 3 (two setae on article 2 and 11 on article 3); the first maxilla inner plate is more setose with 11 setae (six setae); the male gnathopod 1 basis is twice the length of the coxa (1.4×the length of the coxa), the basis has only a short, stubby fringe on its margins (long plumose, dense fringe); gnathopod 1 carpus is much longer than the propodus—1.9× (1.2×); the male gnathopod 2 propodal palm has a large, wide subquadrate mid-palmar tooth (no mid-palmar tooth); dactylus is much shorter than the palm (subequal to the palm); there are also differences in the number and arrangement of robust setae on uropods 1–3 (see figures).   
 Cymadusa tattersalli n. sp. (described above) was originally called Cymadusa setosa. Cymadusa setosa differs from Cymadusa tattersalli by the male gnathopod 1 being weakly setose, with a proportionally smaller coxa, a proportionally longer basis, the merus is produced to form a long and acute anteroventral lobe, the carpus is elongate and narrow. The male gnathopod 2 also differs by having a proportionally longer basis and the propodal palm is nearly transverse and has a mid-palmar tooth.   
 Habitat. Cymadusa setosa occurs on shallow water brown algae, especially Sargassum spp.   
 Distribution. Botany Bay, New South Wales, Australia; Florida, USA; Puerto Rico, Caribbean Sea; Hawaiian Islands and New Caledonia, Pacific Ocean; southern tip of India, Indian Ocean (Map 1).
description: Published as part of Peart, R. A., 2004, A revision of the Cymadusa filosa complex (Crustacea: Amphipoda: Corophioidea: Ampithoidae), pp. 301-336 in Journal of Natural History 38 (3) on pages 324-330, DOI: 10.1080/0022293021000055441, http://zenodo.org/record/4653568