Chevalia freycinet, 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 : 181-185

Chevalia freycinet sp. nov.

urn:lsid:zoobank.org:act:C5C0AFDE-6B3C-4CF3-BA83-C3F9A770694F

( Figs 1–2 , 20–23 )

Holotype: Female, non-ovigerous, 4.8 mm, dissected, (carcass and 1 slide), NMV J71520 , off Freycinet Peninsula , Tasmania, 42°02.2'S 148°38.7'E, 500 m, coarse shelly sand, WHOI epibenthic sled, coll. M.F. Gomon et al., 27 July 1986, station SLOPE 45 . Paratypes: male, 4.4 mm, dissected, NMV J71521 , same location as holotype ; 3 males, 2 females, 2 immature specimens, NMV J21723 , same location as holotype .

Type locality. Off Freycinet Peninsula , Tasmania, 42°2.2'S 148°38.7'E .

Etymology. Named from the type locality as a noun in apposition.

Diagnosis. Antenna 1 subequal to body length, accessory flagellum 3-articulate. Maxilliped outer plate with 3 robust setae. Gnathopod 1 coxa with anterodistal corner not produced. Gnathopod 2 propodus palm oblique, without posterodistal shelf, defined by corner with subacute tooth; Pereopods 5–7 merus, carpus and propodus distal margins with a few long slender plumose setae. Pereopod 7 basis rectilinear, posterodistal corner excavate; carpus posterodistal corner with 3 submarginal robust setae. Uropod 2 outer ramus dorsal margin with row of 3 long plumose setae. Uropod 3 rami longer than peduncle; Telson apical margin truncate.

Description. Based on holotype, female, 4.4 mm, NMV J71520.

Head. Eyes of small size, situated away from lateral cephalic lobe, lateral cephalic lobe subacute.Antennae densely setose. Antenna 1 subequal to body length; peduncular article 1 longer than article 3; primary flagellum with 9 articles; accessory flagellum 3-articulate, article 1 shorter than article 2, article 3 rudimentary. Antenna 2 length 0.7 times length antenna 1; article 4 length subequal article 5; article 5 length 0.9 times flagellum; flagellum with 7 articles. Mandible palp, article 1 length 0.2 times article 2, article 2 length 1.1 times article 3; incisor with 4 teeth, lacinia mobilis with teeth, accessory setal row present, 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 10 robust setae; palp 2-articulated with 4 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; outer plate with a row of apical plumose setae. Maxilliped inner plate subrectangular, apical margin with 4 robust setae and several plumose setae, medial margin with several plumose setae; outer plate shorter than palp article 2, with 3 robust setae and few 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 longer than coxa 2, with anterodistal corner not produced, rounded; basis anterior margin straight, posterior margin convex, margins weakly setose; carpus length 3 times breadth, 1.2 times propodus length, posterior margin lined with setae; propodus length 2.5 times breadth, margins lined with dense setae, palm acute, weakly straight, palm with row of 3 robust setae, without palm defining corner; dactylus recurved. Gnathopod 2 basis anterior margin concave, posterior margin convex, with few slender setae; carpus length 1.6 times breadth, 0.8 times propodus; propodus subchelate, enlarged, posterior margin parallel to anterior margin, palm oblique, without posterodistal shelf, defined by corner with subacute tooth; dactylus not reaching palm corner. Pereopod 3 oostegite present; basis subovate, length 2.4 times breadth; merus rectilinear; carpus length 1.7 times breadth; propodus length 3.3 times breadth. Pereopod 4 oostegite present; basis subovate, length 2.7 times breadth; merus rectilinear; 184 Records of the Australian Museum (2024) Vol. 76 carpus length 1.7 times breadth; propodus length 3.7 times breadth. Pereopods 5–7 merus, carpus and propodus distal margins with a few long slender plumose setae; merus distal corners not produced; dactylus anterior margin with accessory spine. Pereopod 5 oostegite present; basis rectilinear; merus length 1.5 times breadth; carpus length 0.4 times breadth, posterodistal corner with 2 submarginal robust setae; propodus length 3.3 times breadth. Pereopod 6 basis rectilinear, length 2.6 times breadth; merus length 5 times breadth; carpus length 2.2 times breadth, posterodistal corner with 3 submarginal robust setae; propodus length 4.7 times breadth. Pereopod 7 basis rectilinear, length 2.6 times breadth, posterodistal projection absent, corner excavate; merus length 2.8 times breadth; carpus length 3.3 times breadth, posterodistal corner with 3 submarginal robust setae; propodus length 4.3 times breadth.

Pleon. Epimeron 3 posterodistal corner broadly rounded, without notch. Urosomites 1–2 fused. Uropod 1 peduncle length 3.2 times breadth, subequal to outer ramus length, dorsal margin without long plumose setae; rami outer margins minutely pectinate apically, inner margins lined with sub-serrate teeth; inner ramus length 6.9 times breadth, 1.1 times outer ramus, without apical robust setae; outer ramus outer margin with robust seta, without slender setae, with 5 apical robust setae. Uropod 2 peduncle length 1.2 times outer ramus; inner ramus length 7.7 times breadth, 1.1 times outer ramus, without robust setae; outer ramus dorsal margin with row of 3 long plumose setae, apical margin cuticle with 3 teeth and with 4 apical robust setae. Uropod 3 peduncle length 1.3 times breadth, 0.8 times length inner ramus; inner ramus 1.1 times outer ramus, with long apical plumose setae, with robust seta; outer ramus with long apical plumose setae. Telson without pair of denticular patches, apical margin truncate with 2 pairs of plumose setae.

Male (sexually dimorphic characters). Based on paratype, male, 4.4 mm, NMV J71521 . Pereopods without oostegites .

Pereopod 7 basis length 1.9 times breadth, posterodistal corner bevelled.

Remarks. Chevalia freycinet sp. nov. has a very long antenna 1 which is as long as the body, while all other species from Australia and New Zealand have the antenna 1 at around half or less than the body length. Also, the pereopod 4 propodus is more elongate in C. freycinet sp. nov. being 3.7 times length to breadth in comparison to other species. Chevalia freycinet sp. nov. is similar to C. csiro sp. nov. in the gnathopod 2 acute palm and rectangular basis of pereopods 5 to 7. Chevalia freycinet sp. nov. and C. csiro sp. nov. can be separated by the chelation of gnathopod 1, which is simple in C. freycinet sp. nov. while subchelate in C. csiro sp. nov. Both C. csiro sp. nov. and C. freycinet sp. nov. are known from deeper waters at 100 m and 500 m respectively. Both C. freycinet sp. nov. and C. tenui s have a slender overall appearance in body plan in comparison to other Chevalia . These species can be easily separated by the length of the gnathopod 2 dactylus which is much shorter in C. tenuis being only around half the length of the palm.

Distribution. Australia. Tasmania, off Freycinet Peninsula (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 20. Chevalia freycinet sp. nov., female, holotype, 4.8 mm, NMV J71520, Freycinet Peninsula, Tasmania. Scale lines for A1, A2, MX1, MX2 represent 0.1 mm, remainder represent 0.2 mm.

Figure 21. Chevalia freycinet sp. nov., female, holotype, 4.8 mm, NMV J71520, Freycinet Peninsula, Tasmania; male, paratype, 4.4 mm, NMV J71521, Freycinet Peninsula, Tasmania. Scale lines represent 0.2 mm.

Figure 22. Chevalia freycinet sp. nov., female, holotype, 4.8 mm, NMV J71520, Freycinet Peninsula, Tasmania; male, paratype, 4.4 mm, NMV J71521, Freycinet Peninsula, Tasmania. Scale lines represent 0.2 mm.

Figure 23. Chevalia freycinetsp.nov.,female,holotype, 4.8 mm, NMV J71520, Freycinet Peninsula,Tasmania.Scale lines represent0.2 mm.