Elasmopus woodjonesi, 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 : 620-625

Elasmopus woodjonesi sp. nov.

( Figures 17–20 )

Type locality

Eastern side in bay, Pearson Island, Investigator Group, South Australia (33 ◦ 57 ′ 18 ′′ S, 134 ◦ 15 ′ 42 ′′ E).

Type material

Holotype male dissected, 7.5 mm, 3 slides, MV J57155 eastern side in bay, Pearson Island, Investigator Group , South Australia (33 ◦ 57 ′ 18 ′′ S, 134 ◦ 15 ′ 42 ′′ E), 20.0 m, 17 April 1985, coll. G.C.B. Poore ( SA 55 ) . Paratypes: female specimen dissected, 9.1 mm, 3 slides, MV J60984 ; juvenile dissected, 6.2 mm, 1 slide, MV J60985 ; adult male specimen, MV J57147 , northeastern side of Topgallant Island , Investigator Group (33 ◦ 43 ′ 00 ′′ S, 134 ◦ 36 ′ 36 ′′ E), 7 m, 22 April 1985, coll. K. Brandon and G.C.B. Poore ( SA 83 ) . Paratype male specimen, 3 slides, MV J57154 , northeastern side of Topgallant Island , Investigator Group (33 ◦ 43 ′ 00 ′′ S, 134 ◦ 36 ′ 36 ′′ E), 12 m, 21 April 1985, coll. K. Brandon and G.C.B. Poore ( SA 78 ) .

Additional material examined

South Australia. 7 specimens, MV J57149 northeastern side of Topgallant Island, Investigator Group (33 ◦ 43 ′ 00 ′′ S, 134 ◦ 36 ′ 36 ′′ E), 16 m, 22 April 1985, coll. K. Brandon and G.C.B. Poore ( SA 84 ) ; female specimen, MV J57152 , The Hotspot Reef, 5 nm west of north end of Flinders Island, Investigator Group (33 ◦ 40 ′ 30 ′′ S, 134 ◦ 22 ′ 00 ′′ E), 17 m, 19 April 1985, coll. K. Brandon and G.C.B. Poore ( SA 61 ) ; 9 specimens, MV J57153 , The Hotspot Reef, 5 nm west of north end of Flinders Island, Investigator Group (33 ◦ 40 ′ 30 ′′ S, 134 ◦ 22 ′ 00 ′′ E), 17 m, 19 April 1985, coll. K. Brandon and G.C.B. Poore ( SA 65 ) .

Etymology

Named for Fredrick Wood Jones (1879–1954), a distinguished scientist, who in the 1920s, made collections of amphipods from the Investigator Group of Islands, the type locality of this species.

Description

Based on holotype male, 7.5 mm, MV J57155 .

Head. Eyes subovoid; lateral cephalic lobe broad, truncated, anteroventral margin with notch / slit. Antenna 1 longer than antenna 2; peduncular article 1 longer than

article 2, with two robust setae along posterior margin; article 2 longer than article 3; flagellum with 33 articles; accessory flagellum short, tri-articulate. Antenna 2 peduncular article 2 cone gland reaching beyond end of peduncular article 3; article 4 longer in length than article 5; flagellum with 13 articles. Mandible molar well developed, triturative, accessory setal row with three setae; palp well developed, tri-articulate; article 1 about twice as long as broad; article 2 subequal in length to article 3, margin with several long slender setae; article 3 strongly falcate, long (4.5 times as long as broad), longer than article 1, with comb of short robust setae along anterodistal margin and three apical setae. Lower lip outer lobes with two pair of ducts; mandibular lobes apically subacute. Maxilla 1 inner plate subtriangular, with two apical plumose setae.

Pereon. Gnathopod 1 coxa anterior margin concave, anteroventral corner produced, subacute; merus with posterodistal tooth; carpus 1.5 times as long as broad, shorter than propodus; propodus anterior margin without setae, medial surface with setal comb, palm acute, convex, entire, defined by posterodistal corner, with posterodistal robust setae. Gnathopod 2 subchelate, not strongly sexually dimorphic; basis broad; merus with subquadrate distoventral corner; carpus compressed, lobate, projecting between merus and propodus; propodus massive, anterior margin with few short robust setae, posterior margin with few slender setae, medial surface smooth, palm about half length of propodus, sculptured, defined by subquadrate corner, distomedial shelf subtriangular with group of five robust setae, medial quadrate tooth on palmar margin with four

short robust setae; dactylus closing along and reaching end of palm, apically subacute. Pereopods 5–7 narrow distally; basis posterior margin smooth, posterodistal corner weakly rounded; carpus and propodus with long, slender setae along anterior margin; propodus not expanded posterodistally.

Pleon. Epimera 1–2 posteroventral corner subquadrate notch with small subacute spine. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner with subacute spine. Urosomite 1 with single subtriangular carina. Uropod 1 peduncle with one basofacial robust seta. Uropod 2 inner ramus longer than peduncle, longer than outer ramus. Uropod 3 rami subequal in length; inner ramus twice as long as broad; outer ramus longer than peduncle. Telson deeply cleft (more than 66%), lobes divergent, with pair of acute long outer and short inner apical cusps, with three or four long apical robust setae, with pair of lateral plumose setae.

Female (sexually dimorphic characters). Based on paratype female, 9.1 mm, MV J60984 . Gnathopod 2 subchelate, not strongly sexually dimorphic; basis slender .

Remarks

Elasmopus woodjonesi sp. nov. is the second species of Elasmopus reported with an enlarged gnathopod 2 propodus in both sexes. The other, E. spinidactylus , occurs throughout the Indo-Pacific. Male and female specimens of E. woodjonesi sp. nov. have gnathopod 2 basis broad and slender, respectively. The gnathopod 2 propodus palm although similarly sculpted, has a more prominent palm defining corner in females. The distinct unicarinate urosomite 1 is reported in another southern Australian Elasmopus , E. shepherdi sp. nov. Both species also have a mandible palp with long third article and lower lip with two pair of ducts. The gnathopod 2 palm sculpting differentiates E. woodjonesi sp. nov. from other Australian Elasmopus .

Distribution

Australia. South Australia: Investigator Island group; Pearson Island, Topgallant Island, False Island, Flinders Island (current study).

Figures

Figure 17. Elasmopus woodjonesi sp. nov., holotype male, 7.5 mm MV J57155, Pearson Island; paratype female, habitus, 9.1 mm, MV J60984, Topgallant Island, South Australia.

Figure 18. Elasmopus woodjonesi sp. nov., holotype male, 7.5 mm, MV J57155, Pearson Island, South Australia.

Figure 19. Elasmopus woodjonesi sp. nov., holotype male, 7.5 mm, MV J57155, Pearson Island; paratype female, 9.1 mm, MV J60984, Topgallant Island, South Australia.

Figure 20. Elasmopus woodjonesi sp. nov., holotype male, 7.5 mm, MV J57155, Pearson Island, South Australia.