Chevalia aviculae Walker, 1904

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 : 164-168

Chevalia aviculae Walker, 1904

( Figs 7–10 )

Chevalia aviculae Walker, 1904: 288 , pl. 7, fig. 50, pl. 8 fig. 50.― Walker, 1909: 341.― Nayar, 1966: 159, fig. 17b.― Ledoyer, 1967: 133, fig. 19.― Ledoyer, 1972: 233, fig. 53B.― Ledoyer, 1982: 198, fig. 68.― Barnard & Thomas, 1987: 533.

Not Chevalia aviculae .― Shoemaker, 1921: 101 ( Barbados) (= C. mexicana Pearse, 1912 , according to Barnard & Thomas, 1987).― Shoemaker, 1942: 39 (California) (= C. inaequalis ( Stout, 1913) , according to Barnard & Thomas, 1987).―J.L. Barnard, 1962: 17, fig. 5 (California) (= C. inaequalis ( Stout, 1913) , according to Barnard & Thomas, 1987).―J.L. Barnard, 1970: 166, fig. 107 (Hawaii) (= Chevalia sp. , according to Barnard & Thomas, 1987).―J.L. Barnard, 1979: 24 (Galapagos) (= Chevalia sp. , according to Barnard & Thomas, 1987).― Conlan, 1983: 61, fig. 32 (British Columbia) (= C. inaequalis ( Stout, 1913) , according to Barnard & Thomas, 1987) (= Chevalia sp. according to Barnard & Karaman, 1991).― Myers, 1985: 76, fig. 59 ( Fiji) (= Chevalia pacifica , according to Myers, 1995) (= Chevalia sp. according to Lazo-Wasem, 1999).― Myers, 1989: 66 (Society Islands) (= Chevalia aviculae of J. L. Barnard, 1970: 166, fig. 107 (Hawaii) (= Chevalia sp. , according to Barnard & Thomas, 1987)).? Chevalia aviculae .―K.H. Barnard, 1916: 252 (south coast, South Africa).―K.H. Barnard, 1937: 169, fig. 15 (Red Sea, south Arabian coast). ―K.H. Barnard, 1955: 7 ( Mozambique, species list).― Griffiths, 1973: 287 (East coast, South Africa).― Griffiths, 1974a: 243 (East coast, SouthAfrica).― Griffiths, 1974b: 278 (southeast coast, South Africa).― Griffiths, 1975: 109 (west coast, South Africa).― Griffiths, 1976:30 ( South Africa, key only).― Griffiths, 1977: 106 (east coast, South Africa, list only).― Ledoyer, 1979: 28 ( Madagascar).— Wakabara et al., 1991: 73 ( Brazil).― Thomas, 1993: 35 (Florida).― Wakabara & Serejo, 1998: 565 ( Brazil).― Ortiz & Lalana, 2010: 77 ( Cuba).― Paz-Rios & Ardisson, 2013: 150 (Gulf of Mexico).

Syntypes: Four microscope preparations (mountant receding and in poor condition), undissected male, lacking urosome, NHMUK 1905.2 .18.405, East Cheval Paar ; undissected male (originally labelled as female) urosome separated from body, NHMUK 1905.2 .18.406 ( T.90), E. Cheval Paar; dissected female (originally labelled as male), NHMUK 1905.2 .18.407 ( T. 75), Ceylon; dissected mouthparts (corresponding carcass unknown), NHMUK 1905.2 .18.408 ( T. 90), Cheval Paar; 15 specimens (wet), include male “a”, 3.8 mm, female “b”, 3.8 mm, NHMUK 1905.2.18.225–234, Pearl oyster washings, East Cheval and Muttuvaratu Paars, Ceylon, coll. W.A. Herdman, 1902, SS Lady Havelock .

Type locality. East Cheval (ca. 8°40'N 79°46'E) and Muttuvaratu (ca. 7°40'N 79°45'E) Paars, Sri Lanka (originally cited as Ceylon) .

Diagnosis. Antenna 1 length 0.3 times body length, accessory flagellum 2-articulate. Gnathopod 1 coxa subequal to coxa 2, with anterodistal corner slightly produced. Gnathopod 2 carpus subequal to propodus length, propodus palm transverse, sinuous, without posterodistal shelf, defined by subquadrate corner. Pereopod 7 basis subrectangular, posterodistal corner broadly rounded, carpus with 1 submarginal robust seta. Epimeron 3 posteroventral margin broadly rounded. Uropod 3 rami subequal in length to peduncle Telson apical margin concave with rounded central projection.

Description. Based on syntype male “a”, 3.8 mm, syntype female “b”, 3.8 mm, (wet specimens) NHMUK 1905.2.18.225–234, syntype female “c”, (microscope slide), NHMUK 1905.2.18.407.

Head. Eyes of medium size, partially situated in lateral lobe of the head, lateral cephalic lobe subacute. Antennae densely setose. Antenna 1 length 0.3 times body length; peduncular article 1 longer than article 3; primary flagellum with more than 6 articles; accessory flagellum 2-articulate, article 2 rudimentary. Antenna 2 slightly shorter than antenna 1; article 4 length 1.2 times article 5; article 5 length 0.8 times flagellum; flagellum with 7 articles. Mandible palp, article 1 length 0.3 times article 2, article 2 length 1.1 times article 3; incisor with 4 teeth, lacinia mobilis with 3 teeth, accessory setal row with 4 setae, molar triturative. Lower lip, inner lobes and outer lobes separated, inner lobes large and fleshy. Maxilla 1 inner plate with few marginal setae; outer plate with 10 robust setae; palp 2-articulate with 5 apical robust setae and 2 subapical setae. Maxilla 2 inner plate shorter than outer plate, with oblique facial row of plumose setae on outer margin. Maxilliped inner plate subrectangular, apical margin with 4 robust setae and several plumose setae, medial margin without plumose setae; outer plate shorter than palp article 2, with 4 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 subequal to coxa 2, with anterodistal corner slightly produced, subacute; basis anterior margin concave, posterior margin convex, with few setae; carpus length 2.8 times breadth, 1.6 times propodus length, posterior margin setae absent; propodus length twice breadth, margins lined with setae, palm acute, not defined by corner or robust setae; dactylus recurved. Gnathopod 2 coxa with anterodistal margin produced, subacute, ventral margin concave; basis anterior margin slightly concave, posterior margin straight, with few slender setae; carpus length subequal to breadth, 0.9 times propodus; propodus subchelate, massive, posterior margin parallel to anterior margin, palm transverse, sinuous, without posterodistal shelf, defined by subquadrate corner; dactylus not reaching palm corner, with proximal hump. Pereopod 3 basis subovate, length 2.2 times breadth; merus subovate; carpus length 1.7 times breadth; propodus length 2.4 times breadth. Pereopod 4 basis subovate, length 2.2 times breadth; merus subovate; carpus length 1.9 times breadth; propodus length twice breadth. Pereopods 5–7 merus distal corners weakly produced; dactylus anterior margin with accessory spine. Pereopod 5 basis subovate, length subequal to breadth; merus length 1.3 times breadth; carpus length 1.2 times breadth, posterodistal corner with 1 submarginal robust seta; propodus length twice breadth. Pereopod 6 basis subovate, length 1.5 times breadth; merus length 1.5 times breadth; carpus length 1.1 times breadth, posterodistal corner with 1 submarginal robust seta; propodus length 2.1 times breadth. Pereopod 7 basis subrectangular, length 1.8 times breadth, posterodistal corner broadly rounded, not produced; merus length 1.2 times breadth; carpus length 1.1 times breadth, posterodistal corner with 1 submarginal robust seta; propodus length 2 times breadth.

Pleon. Epimeron 3 posteroventral margin broadly rounded, posterodistal corner without notch. Urosomites 1–2 fused. Uropod 1 peduncle length 2.2 times breadth, subequal to outer ramus, dorsal margin with 2 setae; inner ramus inner margin lined with barbed setae, length 5 times breadth, 1.2 times length outer ramus, without apical robust setae; outer ramus outer margin lined with minute spines, apical third of inner margin lined with minute spines, with 3 apical robust setae. Uropod 2 peduncle length 1.3 times outer ramus; inner ramus length 7 times breadth, 1.3 times outer ramus, without robust setae; outer ramus dorsal margin without setae, apical margin cuticle with 3 teeth and with 3 apical robust setae. Uropod 3 peduncle length 1.1 times breadth, 0.9 times length inner ramus; inner ramus 1.1 times outer ramus, with long apical plumose setae, without robust seta; outer ramus with long apical plumose setae and 1 apical robust seta. Telson subquadrate, with a pair of lateral denticular patches; with 3 pairs of dorsal plumose setae: apical margin concave with rounded central projection.

Female (sexually dimorphic characters). Based on syntype female, 3.8 mm, NHMUK 1905.2.18.225–234. Pereopods 3–5 oostegites present, length about 8 times breadth. Pereopod 7 basis subrectangular, length 1.9 times breadth .

Remarks. The re-illustration and redescription of Chevalia aviculae , bring this species into a modern context, allowing comparison with the 18 species described since the original publication of Walker (1904), which established Chevalia as a new genus. The illustration of all mouthparts and antennae are now documented from the syntype series, which were not included in the original description. Gnathopod 2 propodus palm is now considered transverse, where previously it was considered oblique and the shape of pereopod 7 basis posterodistal corner is broadly rounded and not produced.

From 1921 to 1989 the scientific name Chevalia aviculae has been applied to material from locations throughout the Indo-Pacific creating what is now acknowledged as a Chevalia aviculae complex ( Shoemaker, 1921, 1942; J.L. Barnard, 1962, 1970, 1979; Ledoyer, 1982; Conlan, 1983; Myers, 1985). Prior to the current redescription several working groups have also contributed to the refining of species delimitation within the complex ( Barnard & Thomas, 1987; Myers, 1995; Lazo-Wasem, 1999). The current study enables further disambiguation, though stops short of formalizing additional new scientific names without a comprehensive redescription of outstanding groups which would need mouthpart redescription and also benefit from further field collecting to better understand local variation.

Based on characters of gnathopod 2 coxa, basis and propodus, shape of pereopod 7 basis, and telson apical margin, Chevalia aviculae is most similar to C. thomasi . Chevalia aviculae differs from C. thomasi in antenna 1 accessory flagellum is 2-articulate (3-articulate in C. thomasi ), and the shape of uropod 3 peduncle, which is broader than long in Chevalia aviculae (longer than broad in C. thomasi ).

Distribution. Sri Lanka ( Walker, 1904, Nayar, 1966); Southern India ( Nayar, 1966); The Saya de Malha Bank and Cargados, Western Indian Ocean ( Walker, 1909); Madagascar ( Ledoyer, 1967, 1972, 1982).

Figures

Figure 7. Distribution map of Chevalia aviculae Walker, 1904. Stars represent type localities; circles represent additional data points.

Figure 8. Chevalia aviculae Walker, 1904, male “a”, syntype, 3.8 mm, NHMUK 1905.2.18.225–234, East Cheval Paar, Sri Lanka.

Figure 9. Chevalia aviculae Walker, 1904, male “a”, syntype, 3.8 mm, NHMUK 1905.2.18.225–234, East Cheval Paar, Sri Lanka; female “c”, syntype, NHMUK 1905.2.18.408, East Cheval Paar, Sri Lanka. Scale lines represent 0.1 mm except H, UR represent 0.2 mm.

Figure 10. Chevalia aviculae Walker, 1904, male “a”, syntype, 3.8 mm; female “b”, syntype, 3.8 mm, NHMUK 1905.2.18.225–234, East Cheval Paar, Sri Lanka. Scale lines represent 0.1 mm.