Elasmopus carteri, Hughes & Lowry, 2011

Hughes, L. E. & Lowry, J. K., 2011, The genus Elasmopus (Crustacea: Amphipoda: Maeridae) in Australian waters, Journal of Natural History 45 (9 - 10), pp. 579-628 : 589-593

Elasmopus carteri sp. nov.

( Figures 3 , 4 )

Type locality

Ningaloo Reef, near Point Cloates, Western Australia (22 ◦ 6 ′ 34 ′′ S, 113 ◦ 6 ′ 10 ′′ E).

Type material

Holotype, dissected male, 5.0 mm, 3 slides, WAM C45483 . Paratypes, 5 specimens, (no. 1 to 5 DNA sampled by OGL), WAM C45484, Ningaloo Reef, near Point Cloates (22 ◦ 6 ′ 34 ′′ S, 113 ◦ 6 ′ 10 ′′ E), 6.8 m, dead coral head, by hand on SCUBA, 25 May 2009, coll. L.E. Hughes, RV Capricornus , CReefs Ningaloo 2009 (MI WA 1054, NR09-60) .

Additional material examined

Western Australia. Male, dissected, 5.6 mm, 2 slides, AM P83319 reef front, south of Tantabiddy, Ningaloo Reef (21 ◦ 55 ′ 42 ′′ S, 113 ◦ 55 ′ 11 ′′ E), 13 m, coarse sediment, collected by hand on SCUBA, 17 June 2008, coll. N.L. Bruce and M. Blazewicz- Paszkowycz, CReefs 2008 (MI WA 979) ; 4 specimens, AM P80018, reef front, south of Tantabiddy, Ningaloo Reef (21 ◦ 55 ′ 42 ′′ S, 113 ◦ 55 ′ 11 ′′ E), 13 m, coarse sediment, collected by hand on SCUBA, 17 June 2008, coll. N.L. Bruce and M. Blazewicz- Paszkowycz, CReefs 2008 (MI WA 979) ; 3 specimens, AM P.83321, wreck of Chofuko Maru, Ningaloo Reef (22 ◦ 51 ′ 43 ′′ S, 113 ◦ 6 ′ 37 ′′ E) 12 m, dead coral head, by hand on SCUBA, 26 May 2009, coll. L.E. Hughes, RV Capricornus , CReefs Ningaloo 2009 (MI WA 1056, NR09-64) ; 2 specimens, AM P.83320, Cygnet Bay, Cape Leveque, Buccaneer Archipelago (16 ◦ 28 ′ 39 ′′ S, 123 ◦ 02 ′ 46 ′′ E), collected by hand on snorkel, 10 April 2008, coll. J. Jelbart (MI WA 1069); 1 dissected male, 6.0 mm, 3 slides, AM P.83322, Port George IV, Bonaparte Archipelago (15 ◦ 23 ′ 30 ′′ S, 124 ◦ 40 ′ 54 ′′ E), 3 m, off pearl shell in panel, by hand on snorkel, 15 April 2008, coll. J. Jelbart (MI WA 1071) .

Cocos (Keeling) Islands. 3 specimens, AM P.81855, “Surf Shack Drift”, western side of West Island (12 ◦ 9 ′ 34 ′′ S, 96 ◦ 48 ′ 59 ′′ E), 14 m, silty rubble in cave, 15 October 2008, coll. J.K. Lowry (MI WA 857) .

Etymology

Named for the ornithologist Thomas Carter, an early pastoralist of Ningaloo and Point Cloates, the type location of the species.

Description

Based on holotype male, 5.6 mm, WAM C45483 .

Head. Eyes subovoid; lateral cephalic lobe broad, truncated, anteroventral margin with notch / slit. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, longer than article 3, without robust setae along posterior margin; flagellum with 18 articles; accessory flagellum minute, bi-articulate. Antenna 2 peduncular article 2 cone gland reaching beyond end of peduncular article 3; article 4 subequal in length to article 5; flagellum with seven articles. Mandible molar well developed, triturative,; accessory setal row with 3 setae; palp tri-articulate; article 1 about twice as long as broad, shorter than article 2; article 2 shorter than article 3, with many slender marginal and apical setae; article 3 strongly falcate, short (twice as long as broad), longer than article 1, with comb of short robust setae along anterodistal margin and six slender apical setae. Lower lip outer lobes with single pair of ducts; mandibular lobes apically rounded. Maxilla 1 inner plate subtriangular, with two apical plumose setae.

Pereon. Gnathopod 1 coxa anterior margin concave, anteroventral corner produced, rounded; merus with posterodistal tooth; carpus twice as long as broad, subequal in length to propodus, with rows of slender setae covering surface; propodus anterior margin with many rows of long slender setae, medial surface without setal comb, palm acute, convex, entire, defined by posterodistal corner, with posterodistal robust setae. Gnathopod 2 subchelate; basis slender; merus with rounded distoventral corner; carpus compressed, lobate, projecting between merus and propodus; propodus expanded, anterior margin with short slender setae, posterior margin with long slender setal bunches, medial surface with rows of short slender setae palm acute, smooth, without posterodistal corner or robust setae, distomedial shelf subtriangular with groups of robust setae, subpalmar seam with short subquadrate projection, without posterodistal robust setae; dactylus closing along and reaching end of palm, apically subacute. Pereopod 4 coxa posteroventral lobe slightly developed, with acute posteromedial corner. Pereopods 5–7 narrow distally; basis slightly expanded, posterior margin castelloserrate; propodus not expanded posterodistally; dactylar unguis simple. Pereopod 5 basis posterior margin straight, posteroventral corner broadly rounded; carpus and propodus with few or no long, slender setae along anterior margin. Pereopod 6 basis posterior margin tapering distally, posteroventral corner subquadrate. Pereopod 7 basis posterior margin convex, posteroventral corner broadly rounded.

Pleon. Epimera 1–2 posteroventral corner notched with small subacute tooth. Epimeron 3 ventral margin smooth, posterior margin smooth, posterodistal corner with two small robust spines. Urosomite 1 smooth, without carina. Uropod 1 peduncle with two basofacial setae. Uropod 2 rami subequal; inner ramus subequal in length to peduncle. Uropod 3 rami distally truncated, apical robust setae short; inner ramus long (twice as long as broad), shorter in length to outer ramus; outer ramus longer than peduncle. Telson deeply cleft (more than 66%), as long as broad, lobes apically truncated, apices acute, with longer outer and shorter inner apices, each lobe with two short and two long apical robust setae and pair of lateral plumose setae.

Remarks

The distal subpalmar tooth of male gnathopod 2 is present in E. ecuadorensis hawaiensis Schellenberg, 1938 of Ledoyer (1978), E. nanshaensis Ren, 1998 , E. carteri sp. nov., E. pseudaffinis Schellenberg, 1938 and E. puteus Appadoo and Myers, 2003 . In E. souillacensis Appadoo and Myers, 2003 the propodus has a similarly placed tooth but it originates from the palmar margin. These species are also similar in the mandibular palp third article short (twice as long as broad), gnathopod 1 propodus without a medial setal comb and elongate telson with divergent lobes. In E. carteri sp. nov., E. ecuadorensis hawaiensis (of Ledoyer 1978) and E. pseudaffinis the pereopods 5–7 basis posterior margins are castelloserrate, weakly crenulate and serrate, respectively whereas in E. puteus and E. souillacensis the margins are smooth.

The relationship between E. carteri sp. nov. and E. nanshaensis is difficult to place. Ren (1998) specifically distinguishes E. nanshaensis from E. serraticus based on the pereopod 6 basis posterior margin castelloserrate with square marginal teeth. This character also separates E. carteri sp. nov., which has pereopod 6 castelloserrate with rounded teeth along the posterior margin.

The pereopod 6 pectinate posterior margin of the basis is present on three species recorded from tropical Australia, E. carteri sp. nov., E. pectenicrus and E. leveque sp. nov. These three species have the rows of slender setae on the gnathopod 2 propodus but the subpalmar tooth distinguishes E. carteri sp. nov.

Distribution

Australia. Western Australia. Ningaloo reef, Cape Leveque, Port George IV (current study); Cocos (Keeling) Islands (current study).

Figures

Figure 3. Elasmopus carteri sp. nov., holotype male, 5.6 mm WAM C45483, Ningaloo Reef, Western Australia.

Figure 4. Elasmopus carteri sp. nov., holotype male, 5.6 mm, WAM C45483, Ningaloo Reef, Western Australia.