Chevalia csiro, Springthorpe & Hughes, 2024

Springthorpe, Roger T. & Hughes, Lauren E., 2024, Re-description of Chevalia aviculae Walker, 1904, five new species and new records of Chevaliidae from Australia and New Zealand (Crustacea: Peracarida: Amphipoda: Senticaudata), Records of the Australian Museum 76 (3), pp. 157-194 : 177-181

Chevalia csiro sp. nov.

urn:lsid:zoobank.org:act:5D7DEB08-3849-4EAE-926C-5456CCB00FEA

( Figs 1–2 , 17–19 )

Holotype: Male, 5.8 mm, dissected, (carcass and 2 slides), AM P.100390, about 90 km west of Dongara , Western Australia, ca. 29°S 114°E, ca. 100 m, RV Sprightly, 10 November 1976, station 31 . Paratypes: ovigerous female, 6.7 mm, dissected, (carcass and 1 slide), AM P.100391; 4 males, 5.8–6.7 mm, 4 females, 5.8–6.7 mm, 4 ovigerous females, 5.8–6.7 mm, 5 juveniles, 5 mm, WAM C71209 , same location as holotype ; many specimens, AM P.100392, same location as holotype .

Type locality. About 90 km west of Dongara , Western Australia, ca. 29°S 114°E .

Etymology. Named for the Commonwealth Scientific and Industrial Research Organisation (Fisheries Division) (CSIRO) for their donations of amphipod collections over many years.

Diagnosis. Antenna 1 length 0.52 times body length. accessory flagellum 3-articulate. Gnathopod 1, with anterodistal corner not produced, rounded. Gnathopod 2 propodus palm transverse to oblique, with posterodistal shelf, distal round excavation large, defined by corner with subacute tooth. Pereopod 7 basis rectilinear; carpus posterodistal corner with 4 submarginal robust setae; Uropod 1 peduncle slightly longer than broad; Uropod 2 outer ramus dorsal margin with row of 4 long plumose setae. Uropod 3 rami shorter than peduncle. Telson apical margin convex.

Description. Based on holotype male, 5.8 mm, AM P. 100390 and paratype ovigerous female, 6.7 mm, AM P.100391.

Head. Eyes of large size, partially situated in lateral lobe of the head, lateral cephalic lobe subacute. Antennae densely setose. Antenna 1 length 0.52 times body length; peduncular article 1 longer than article 3; primary flagellum with 11 articles; accessory flagellum 3-articulate, article 1 shorter than article 2, article 3 rudimentary. Antenna 2 slightly shorter than antenna 1; article 4 length 1.1 times article 5; article 5 length 0.8 times flagellum; flagellum with 8 articles. Mandible palp, article 1 length 0.2 times article 2, article 2 sub-equal in length to article 3; incisor with 4 teeth, lacinia mobilis with 2 teeth, accessory setal row with 3 setae, molar triturative. Lower lip, inner lobes and outer lobes separated, inner lobes large and fleshy. Maxilla 1 inner plate with a few marginal setae; outer plate with 9 robust setae; palp 2-articulated with 5 apical robust setae and 1 slender subapical seta. Maxilla 2 inner plate shorter than outer plate, with oblique facial row of plumose setae on outer margin; outer plate with a row of apical plumose setae. Maxilliped inner plate subrectangular, apical margin with 3 robust setae and several plumose setae, medial margin lined with many plumose setae; outer plate shorter than palp article 2, with 7 robust setae and row of plumose setae on medial and facial margins, with 2 apical plumose setae; palp, article 2 longer than articles 3 and 4 combined, article 4 with 1 long distal seta.

Pereon. Gnathopod 1 coxa shorter than coxa 2, with anterodistal corner not produced, rounded; basis anterior margin straight, posterior margin convex, margins weakly setose; carpus length 2.2 times breadth, 1.2 times propodus length, posterior margin lined with setae; propodus length 1.8 times breadth, margins lined with dense setae, palm subchelate, weakly convex, palm distal section with 4 evenly spaces robust setae, without palm defining corner; dactylus slightly overreaching palm. Gnathopod 2 basis anterior and posterior margins straight, with few slender setae; carpus length 1.2 times breadth, 0.5 times propodus; propodus subchelate, massive, posterior margin parallel to anterior margin, palm oblique, with posterodistal shelf, distal round excavation large, defined by corner with subacute tooth; dactylus not reaching palm corner. Pereopod 3 oostegite present; basis proximally narrow distally broad, length 2.3 times breadth; merus subovate; carpus length 1.2 times breadth; propodus length 2.4 times breadth. Pereopod 4 oostegite present; basis proximally narrow distally broad, length 2.3 times breadth; merus subovate; carpus length 1.1 times breadth; propodus length 2.3 times breadth. Pereopods 5–7 merus, carpus and propodus distal margins without long slender plumose setae; merus distal corners weakly produced; dactylus anterior margin with accessory spine. Pereopod 5 oostegite present; basis rectilinear; merus length 0.9 times breadth; carpus length 1.4 times breadth, posterodistal corner with 4 submarginal robust setae; propodus length 2.7 times breadth. Pereopod 6 basis rectilinear, length 2.4 times breadth; merus length 3 times breadth; carpus length twice breadth, posterodistal corner with 4 submarginal robust setae; propodus length 3.1 times breadth. Pereopod 7 basis rectilinear, length 2.5 times breadth, posterodistal projection absent; merus length 2.3 times breadth; carpus length 1.9 times breadth, posterodistal corner with 4 submarginal robust setae; propodus length 3.3 times breadth.

Pleon. Epimeron 3 posterodistal corner narrowly rounded, without notch. Urosomites 1–2 fused. Uropod 1 peduncle length 1.3 times breadth, 0.4 times outer ramus, dorsal margin with long plumose setae; rami outer margins minutely pectinate apically, inner margins lined with sub-serrate teeth; inner ramus length 10.6 times breadth, 1.2 times outer ramus, without apical robust setae; outer ramus outer margin lined with 3 slender setae, with 4 apical robust setae. Uropod 2 peduncle length 0.9 times outer ramus; inner ramus length 9.5 times breadth, 1.4 times outer ramus, without robust setae; outer ramus dorsal margin with row of 4 long plumose setae, apical margin cuticle with 3 teeth and with 4 apical robust setae. Uropod 3 peduncle length subequal to breadth, 2.3 times length inner ramus; inner ramus 0.8 times outer ramus, with long apical plumose setae, without robust seta; outer ramus with long apical plumose setae. Telson apical margin convex with 4 pairs of plumose setae.

Remarks. Chevalia csiro sp. nov. and C. freycinet sp. nov. have the bases of pereopods 5 to 7 rectangular while other species have more ovate bases. In C. csiro sp. nov. the gnathopod 2 palm excavation is more pronounced with a distal shelf present where in C. freycinet sp. nov. the shelf is absent, and the palmar excavation is poorly developed.

Distribution. Australia. Western Australia: west of Dongara (current study).

Figures

Figure 1. Distribution map of Australian and New Zealand Chevaliidae species. Stars represent type localities; circles represent additional data points.

Figure 2. Field guide to Australian and New Zealand Chevaliidae species.

Figure 17. Chevalia csiro sp. nov., male, holotype, 5.8 mm,AM P.100390, west of Dongara, WesternAustralia. Scale lines for UL, MX1, MX2, LL, represent 0.1 mm, remainder represent 0.2 mm.

Figure 18. Chevalia csiro sp.nov., male, holotype,5.8 mm,AM P.100390,west of Dongara,Western Australia; ovigerous female, paratype, 6.7 mm, AM P.100391, west of Dongara, Western Australia. Scale lines represent 0.5 mm.

Figure 19. Chevalia csiro sp.nov., male, holotype,5.8 mm,AM P.100390, west of Dongara,WesternAustralia; ovigerous female, paratype, 6.7 mm, AM P.100391, west of Dongara, Western Australia. Scale lines represent 0.2 mm.