Mallacoota barnardi, Hughes, 2011

HUGHES, L. E., 2011, New species of Hoho, Mallacoota and Parelasmopus (Maeridae: Amphipoda) from Australian waters, Zootaxa 2955 (1), pp. 1-79 : 32-38

Mallacoota barnardi sp. nov.

(Figs 21, 22)

Type material. Holotype: male, 4.5 mm, dissected, 3 slides, AM P.85203 . Paratypes: 1 female, 4.0 mm, dissected, 3 slides, AM P.85204, "Surf Shack Drift" dive site, western side of West Island (12°09'35"S 96°48'59"E), 10 m, rubble with epiphytes, 15 October 2008, coll. J.K. Lowry and L.E. Hughes ( MI WA 859 ) ; 7 males, 4 females, AM P.81838, "Surf Shack Drift" dive site, western side of West Island (12°09'35"S 96°48'59"E), 10 m, rubble with epiphytes, 15 October 2008, coll. J.K. Lowry and L.E. Hughes ( MI WA 859 ) .

1 male, AM P.81835, "Rose Wall" dive site, near Horsburgh Island (12°05'45"S 96°50'32"E), 13.8 m, green calcareous algae Halimeda sp. , 12 October 2008, coll. K.B. Attwood ( MI WA 827 ) ; 1 juvenile, AM P.81839, "Rose Wall" dive site, near Horsburgh Island (12°05'45"S 96°50'32"E), 11 m, rubble and calcareous green algae Halimeda sp. , 12 October 2008, coll. L.E. Hughes ( MI WA 830 ) ; 3 males, 2 females, 1 juvenile, AM P.81843, "Two Trees" dive site, western side of West Island (12°09'35"S 96°48'59"E), 10.8 m, coral Acropora sp. plate and rubble, 15 October 2008, coll. L.E. Hughes and K.B. Attwood ( MI WA 854 ) ; 2 males, 1 female, AM P.81842, "Winter Wall" dive site, near Horsburgh Island (12°05'15"S 96°50'14"E), 9 m, rubble, 12 October 2008, coll. K.B. Attwood ( MI WA 834 ) ; 4 females, AM P.81847, "Winter Wall" dive site, near Horsburgh Island (12°05'15"S 96°50'14"E), 9.5 m, rubble under plate coral, 12 October 2008, coll. K.B. Attwood ( MI WA 835 ) ; 3 males, 5 females, AM P.81844, "Winter Wall" dive site, near Horsburgh Island (12°05'15"S 96°50'14"E), 9 m, rubble with epiphytes, 12 October 2008, coll. J.K. Lowry ( MI WA 837 ) ; 4 males, 5 females, 2 juveniles, AM P.81841, centre of lagoon (12°08'50"S 96°51'13"E), 8 m, Acropora sp. coral dead with red epiphytic algae, 14 October 2008, coll. K.B. Attwood and L.E. Hughes ( MI WA 845 ) ; 2 males, 7 females, AM P.81845, coral bommie near wreck of the Flying Boat Catalina JX435, near Horsburgh Island (12°05'48"S 96°51'31"E), 7.2 m, coarse sticks of rubble, 9 October 2008, coll. K.B. Attwood ( MI WA 809 ) ; 3 males, 4 females, 1juvenile, AM P.81846, coral bommie near wreck of the Flying Boat Catalina JX435, near Horsburgh Island (12°05'48"S 96°51'31"E), 7.2 m, rubble, 9 October 2008, coll. K.B. Attwood ( MI WA 795 ) ; 4 males, 3 females, AM P.81840, north-east section of the lagoon (12°06'22"S 96°52'12"E), 5.8 m, large coral rubble, 9 October 2008, coll. J.K. Lowry ( MI WA 806 ) ; 1 male, 1 female, AM P.81836, northern side of Direction Island (12°05'05"S 96°52'54"E), 8 m, large pieces of coral rubble and sediment, 8 October 2008, coll. J.K. Lowry ( MI WA 783 ) .

Christmas Island. 1 dissected male, 4.3 mm, 4 slides, AM P.85205, MV Eidsvold Wreck (10°26'34"S 105°39'32"E), 11.6 m, algae on rubble, 24 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 949 ); 1 dissected female, 4.5 mm, 3 slides, AM P.85206, MV Eidsvold Wreck (10°26'34"S 105°39'32"E), 11.6 m, algae on rubble, 24 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 949 ); 10+ specimens, AM P.81710, MV Eidsvold Wreck (10°26'34"S 105°39'32"E), 11.6 m, algae on rubble, 24 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 949 ); 20+ specimens, AM P.81689, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 14 m, rubble with fine red algae, 23 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 933 ); 20+ specimens, AM P.81694, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 12 m, fine red algae and dead coral Acropora sp. , 23 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 930 ); 4 males and 7 females, AM P.81699, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 17.5 m, rubble, 23 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 927 ); 1 male and 4 females, AM P.81714, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 12.1 m, rubble with black sponge, 23 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 928 ); 30+ specimens, AM P.81675, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 14.8 m, rubble with fine brown algae, 23 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 926 ); 3 females, AM P.81804, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 10.4 m, rubble with red algae, 23 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 929 ); 1 female, AM P.81719, “ Chicken Farm ” dive site (10°24'56"S 105°41'03"E), 14–15 m, sand, 23 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 932 ); 4 males and 4 females, AM P.81680, “ Million Dollar Bommie ” dive site (10°27'22"S 105°38'11"E), 14 m, coral Acropora sp. with tufted algae, sand and red algae, 18 October 2008, coll. J.K. Lowry and K.B. Attwood, MV Fastwater ( MI WA 867 ); 15+ specimens, AM P.81717, “ Million Dollar Bommie ” dive site (10°27'22"S 105°38'11"E), 14 m, coral Acropora sp. with tufted algae, sand and red algae, 18 October 2008, coll. J.K. Lowry and K.B. Attwood, MV Fastwater ( MI WA 867 ); 10+ specimens, AM P.81685, “ Million Dollar Bommie ” dive site (10°27'22"S 105°38'11"E), 14 m, dead coral Acropora sp. with red algal epiphytes, 18 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 874 ); 23 specimens, AM P.81690, “ Million Dollar Bommie ” dive site (10°27'22"S 105°38'11"E), 12.8 m, dead plate of coral Acropora sp. , 18 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 863 ); 1 male, AM P.81707, “ Perpendicular Wall ” dive site (10°26'50"S 105°33'39"E), 35 m, dead coral, 22 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 922 ); 2 males, 3 females, AM P.81726, “ Perpendicular Wall ” dive site (10°26'50"S 105°33'39"E), 22 m, encrusted dead coral, 22 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 923 ); 3 males, 4 females, AM P.81692, “ Perpendicular Wall ” dive site (10°26'50"S 105°33'39"E), 16 m, encrusted plastic rope, 22 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 919 ); 2 males, 4 females, 1 juvenile, AM P.81697, “ Perpendicular Wall ” dive site (10°26'50"S coll. J.K. Lowry, MV Fastwater ( MI WA 935 ); 1 male, AM P.81681, “ The Morgue ” dive site (10°24'56"S 105°41'03"E), 13.7 m, red algae, 23 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 941 ); 2 females, AM P.81696, “ The Morgue ” dive site (10°24'56"S 105°41'03"E), 9.5 m, rubble, 23 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 939 ); 30+ specimens, AM P.81723, “ The Morgue ” dive site (10°24'56"S 105°41'03"E), 18 m, rubble, 23 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 937 ); 3 males, 5 females, AM P.81725, “ The Morgue ” dive site (10°24'56"S 105°41'03"E), 20 m, rubble under overhang, 23 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 936 ); 10+ specimens, AM P.81721, “ The Morgue ” dive site(10°24'56"S 105°41'03"E), 15.5 m, rubble with brown algae, 23 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 942 ); 2 females, AM P.81703, “ The Morgue ” dive site (10°24'56"S 105°41'03"E), 18 m, sponges with hydroids, 23 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 938 ); 4 females, AM P.81682, Boat Cave (10°27'20"S 105°34'05"E), 14.2 m, rubble, 22 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 911 ); 10 specimens, AM P.81711, Boat Cave (10°27'20"S 105°34'05"E), 14 m, rubble, 22 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 915 ); 5 males, 4 juveniles, AM P.81713, Boat Cave (10°27'20"S 105°34'05"E), 8.6 m, rubble, 22 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 913 ); 18 specimens, AM P.81716, Boat Cave (10°27'20"S 105°34'05"E), 10.5 m, rubble, green calcareous algae Halimeda sp. , turfing red algae, 22 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 912 ); 40+ specimens, AM P.81724, MV Eidsvold Wreck (10°26'34"S 105°39'32"E), 10.6 m, algae covered plate coral Acropora sp. , 24 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 946 ); 15 specimens, AM P.81722, MV Eidsvold Wreck (10°26'34"S 105°39'32"E), 8.2 m, dead coral Acropora sp. with red algae and silt, 24 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 945 ); 20+ specimens, AM P.81708, MV Eidsvold Wreck (10°26'34"S 105°39'32"E), 8 m, dead coral, 24 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 948 ); 2 males, 1 female, 2 juveniles, AM P.81712, undercut at submarine cave entrace, Lost Lake Cave (10°27'54"S 105°36'39"E), 30 m, sponge and algae covered plate coral, 24 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 951 ); 10+ specimens, AM P.81676, undercut at submarine cave entrace, Lost Lake Cave (10°27'54"S 105°36'39"E), 22 m, algae on dead coral plate Acropora sp. , 24 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 953 ); 1 male, 2 females, AM P.81706, undercut at submarine cave entrace, Lost Lake Cave (10°27'54"S 105°36'39"E), 35 m, coral rubble, 24 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 950 ); 16 specimens, AM P.81700, undercut at submarine cave entrance, Lost Lake Cave (10°27'54"S 105°36'39"E), 30 m, frilly red algae on dead plate coral, 24 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 952 ); 14 specimens, AM P.81684, undercut at submarine cave entrace, Lost Lake Cave (10°27'54"S 105°36'39"E), 17 m, rubble, 24 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 954 ); 3 males, 1 juvenile, AM P.81705, Merriel Beach (10°28'26"S 105°33'29"E), 8.8 m, dead coral, 21 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 902 ); 18 specimens, AM P.81698, Merriel Beach (10°28'26"S 105°33'29"E), 13 m, rubble, 21 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 903 ); 6 females, AM P.81678, Merriel Beach (10°28'26"S 105°33'29"E), 15.5 m, rubble, 21 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 904 ); 2 males, 1 female, AM P.81693, Merriel Beach (10°28'26"S 105°33'29"E), 13.6 m, rubble and green algae, 21 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 901 ); 1 male, 1 juvenile male, AM P.81683, south of Smiths Point (10°26'02"S 105°39'38"E), 22 m, dead coral and algae, 20 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 894 ); 15+ specimens, AM P.81695, south of Smiths Point (10°26'02"S 105°39'38"E), 15.8 m, rubble with brown algae, 20 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 892 ); 30+ specimens, AM P.81720, south of Smiths Point (10°26'02"S 105°39'38"E), 11–15 m, rubble with sediment, 20 October 2008, coll. J.K. Lowry and K.B. Attwood, MV Fastwater ( MI WA 891 ); 1 male, 2 females, AM P.81704, Submarine Rock (10°27'42"S 105°35'03"E), 15.7 m, delicate red algae, 19 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 875 ); 1 male, 1 female, AM P.81687, Submarine Rock (10°27'42"S 105°35'03"E), 13.8 m, fleshy green algae, 19 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 876 ); 2 males, 3 females, AM P.81674, Submarine Rock (10°27'42"S 105°35'03"E), 14.1 m, rubble with epiphytes, 19 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 880 ); 1 male, 13 females, AM P.81677, Thundercliff Cave (10°27'58"S 105°36'24"E), 30 m, algae covered rubble, 19 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 889 ); 20 specimens, AM P.81679, Thundercliff Cave (10°27'58"S 105°36'24"E), 20 m, green calcareous algae Halimeda sp. and algae covered rubble, 19 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 888 ); 3 males, 5 females, 2 juveniles, AM P.81701, Thundercliff Cave (10°27'58"S 105°36'24"E), 12 m, red algae, 19 October 2008, coll. L.E. Hughes, MV Fastwater ( MI WA 885 ); 30+ specimens, AM P.81673, eous algae Halimeda sp. , 18 October 2008, coll. L.E. Hughes and K.B. Attwood, MV Fastwater ( MI WA 868 ); 30+ specimens, AM P.81686, West White Beach (10°27'41"S 105°34'54"E), 8 m, dead coral encrusted with epiphytes, 18 October 2008, coll. L.E. Hughes and K.B. Attwood, MV Fastwater ( MI WA 871 ); 3 males, 3 females, AM P.81834, West White Beach (10°27'41"S 105°34'54"E), 8.4 m, rubble and rocks, 18 October 2008, coll. L.E. Hughes and K.B. Attwood, MV Fastwater ( MI WA 872 ); 2 males, 1 juvenile male, 3 indet. juveniles, AM P.81688, West White Beach (10°27'41"S 105°34'54"E), 12.4 m, rubble with grey sponge and green algae, 18 October 2008, coll. L.E. Hughes and K.B. Attwood, MV Fastwater ( MI WA 873 ); 24 specimens, AM P.81702, Winnifred Beach (10°29'48"S 105°32'44"E), 17 m, dead coral with encrusting algae, 21 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 907 ); 17 specimens, AM P.81718, Winnifred Beach (10°29'48"S 105°32'44"E), 20–25 m, dead coral with encrusting algae, 21 October 2008, coll. J.K. Lowry, MV Fastwater ( MI WA 906 ); 30+ specimens, AM P.81715, Winnifred Beach (10°29'48"S 105°32'44"E), 18.5 m, rubble with red epiphytes, 21 October 2008, coll. K.B. Attwood, MV Fastwater ( MI WA 908 ) .

Type locality. Western side of West Island, Cocos (Keeling) Islands, Indian Ocean, (12°09'35"S 96°48'59"E) .

Etymology. Name for J.L. Barnard who established the genus.

Description. Based on holotype, male, 4.5 mm, AM P.85203.

Pereon. Head eyes ovate to reniform; lateral cephalic lobe broad, apically truncated, anteroventral margin with notch/slit, anteroventral corner rounded. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, with 1 robust setae along posterior margin; peduncular article 2 subequal in length to article 3; accessory flagellum minute, with 2 articles; primary flagellum with 11 articles. Antenna 2 peduncular article 2 cone gland reaching to end of peduncular article 3, with 5 articles. Lower lip inner lobes present, outer lobes with single pair of ducts, mandibular lobes apically subacute. Mandible accessory setal row well developed with 3 setae; molar well developed; mandibular palp, 3-articulate; article 1 at least 3 times as long as broad, longer than article 2; article 2 subequal to article 3, without setae; article 3 rectolinear, short (about twice as long as broad), shorter than article 1 with 2 apical setae.

Pereon. Gnathopod 1 coxa anterior margin concave, anteroventral corner produced, rounded, posteroventral corner with notch; merus with sharp posterodistal tooth; carpus about 2 times as long as broad, carpus subequal in length to propodus; propodus medial surface with setal comb, palm acute, straight, entire, defined by posterodistal corner with robust setae. Gnathopod 2 subchelate; coxa posteroventral with corner notch; basis slender, without anterodistal robust setae, anterodistal lobes as a well developed paired; carpus compressed, lobate, projecting between merus and propodus; propodus expanded, palm acute, straight, sculptured, with well defined corner, palm about two thirds length of propodus, subtriangular distomedial shelf with robust setae, palm with 3 excavations and 3 subacute teeth, defined by posteroventral tooth, without posterodistal robust setae, palmar margin without robust setae, subpalmar surface smooth; dactylus without posteroproximal shelf, posterior margin with four rounded bumps along margin, dactylus closing along palm, not reaching end of palm, apically blunt. Pereopod 4 coxa posteroventral lobe well developed, with rounded posteromedial corner. Pereopods 5–7 broad distally; basis expanded, convex, posterior margin without long slender setae, posteroventral corner broadly rounded; merus and carpus immensely broadened; carpus and propodus with a few long, slender setae along posterior margin; dactylar ungues simple. Pereopods 6 –7 basis posterior margin weakly serrate. Pereonite 7 without carina.

Pleon. Pleonites 1–3 dorsally smooth. Epimera 1–2 posteroventral corner acutely produced. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner with small acute tooth. Urosomite 1 without carina. Uropod 1 peduncle with 1 basofacial seta. Uropod 2 rami inner ramus longer than outer ramus. Uropod 3 rami distally truncated, apical robust setae long and short; inner ramus short, about 0.5 times outer ramus; inner ramus short (length 1 to 1.9 times breadth); outer ramus short, subequal to peduncle. Telson deeply cleft, longer than broad, lobes divergent, tapering distally, each lobe with subequal inner and outer apical cusps, each lobe with 2 long apical robust setae.

Female (sexually dimorphic characters), based on AM P.85204. Gnathopod 2 basis anterodistal corner subquadrate; carpus short, not lobate, enclosed by merus and propodus; propodus linear, palm acute, smooth, about one third length of propodus, without distomedial shelf, without teeth, defined by posteroventral corner with robust setae; dactylus apically subacute.

Remarks. Mallacoota barnardi sp. nov. was the most abundant amphipod species recorded at both Cocos

This species is aligned with Mallacoota magnimerus from Mauritius, M. subinsignis of Madagascar and M. sculpulosa from Queensland, Australia. Shared characters include the distinctive form of the male gnathopod 2 and the pereopods 6–7 expanded articles. For mature males the pereopod 6 carpus is expanded in M. subinsignis , weakly expanded in M. barnardi sp. nov., not expanded in M. magnimerus and M. scopulosa . Mallacoota barnardi sp. nov. and M. subinsignis both have the gnathopod 2 dactylus posterior margin lined with rounded teeth, which is unknown elsewhere in the genus.

This grouping of closely related species is supported by their geographic distributions, with M. scopulosa , M. barnardi sp. nov., M. magnimerus , and M. subinsignis from Queensland, Cocos (Keeling) Islands, Christmas Island, Mauritius and Madagascar, respectively.

Distribution. Australia. Indian Ocean: Cocos (Keeling) Islands and Christmas Island (current study).