Thaumodon poorei, Lowry & Stoddart, 1995

Lowry, J. K. & Stoddart, H. E., 1995, New lysianassoid genera and species from south-eastern Australia (Crustacea: Amphipoda), Records of the Australian Museum 47 (1), pp. 7-25 : 9-12

Thaumodon poorei n.sp.

Figs 2 , 3

Type material. HOLOTYPE, female, 14 mm, NMV J25814 , 1 PARATYPE, male, 11.5 mm, NMV J3787 and 3 PARATYPES, female, AM P40431: off Crib Point , Western Port, Victoria, Australia, 38°21'S 145°14'E, Smith-McIntyre grab, weed and mud, 7 m, A.J. Gilmour and Marine Studies Group on FV Melita, 4 September 1964, stn CPBS-B1 . PARATYPE female, NMV J3786, Crawfish Rock , Western Port, Victoria, Australia, Underwater Research Group, 10 November 1968 . 4 PARATYPES, NMV J3788, Tankerton Jetty, Western Port, Victoria, 6 m, Underwater Research Group , 22 November 1970 .

Description. Based on holotype female, 14 mm and paratype male, 11.5 mm. Head and body: with scattered setae. Head: deeper than long, lateral cephalic lobe large, broad, distally truncated; rostrum absent; eyes oval, not enlarged in adult male. Antenna 1: short, 0.14 x body; peduncular article 1 short, length 1.4 x breadth, with small midmedial spine; peduncular article 2 short, 0.46 x article 1; peduncular article 3 long, 0.25 x article 1; accessory flagellum long, 0.7 x primary flagellum, 6-articulate, article 1 short, 1.2 x article 2 (male short, 1.4 x); flagellum 9-articulate (male 9), without callynophore in female (weak 1- field callynophore in male), without flagellar robust setae,calceoli absent in female and male. Antenna 2: subequal in length to antenna 1 in female and male; peduncle without brush setae in female or male, weakly geniculate between peduncular articles 3---4, article 3 short,peduncular articles 4 and 5 not enlarged in female or male;flagellum 8-articulate (male 7), calceoli absent in female and male.

Mouthpart bundle: subquadrate. Epistome and upper lip:separate, epistome slightly produced, rounded, upper lip slightly produced, rounded. Mandible: incisors symmetrical, very large, with slightly convex margins; lacinia mobilis absent; accessory setal row, left and right rows each with 3 long, slender, simple setae; intermediate setae absent; molar a reduced finely setose flap; mandibular palp attached extremely proximally; article 1 short, length 1.6 x breadth; article 2 slender, length 5.8 x breadth, 2 x article 3, with 8 distal A2-setae, without D2-setae; article 3 slender, blade-like, long, length 3.75 x breadth, without A3-setae, without D3- setae (male 3), with 3 apical E3-setae. Maxilla 1: inner plate narrow,with 2 pappose setae; outer plate with 11 'setal-teeth in modified 6/5 arrangement, setal-teeth without cusps, ST1 to ST7 large, slender, curved, smooth,without cusps, ST7 contiguous with ST6; STA large,slender, curved, slightly displaced from STB and contiguous with STC, STB large, slender, curved, without cusps, STC large, slender, curved, slightly displaced from STB and contiguous with STA and STD, without cusps, STD large, slender, curved, contiguous with STB-STC and ST7, without cusps; palp large, 2- articulate,with serrate apical margin, without subterminal setae, robust flag seta present on distolateral corner, distomedial margin serrate. Maxilla 2: inner plate broad, outer plate narrow, inner plate length 1 x outer plate. Maxilliped: inner plate large, subrectangular, with 3 apical long robust setae, oblique setal row reduced with 3 simple setae; outer plate medium size, subovate, without apical slender setae, without apical robust setae, medial setae absent, submarginal setae vestigial; palp large,4-articulate,article 2 slender, length 2.3 x breadth, article 3 long,slender, dactylus reduced, with 2 terminal and 1 subterminal setae, unguis present.

Gnathopod 1: simple; coxa large, about as long as Lowry & Stoddart: Lysianassoids 11 coxa 2, anterior margin concave, anteroventral corner produced, rounded, posterior margin straight; basis long, slender, length 3.9 x breadth, anterior margin smooth, with simple setae; ischium long, length 1.7 x breadth; merus, posterior margin with long simple setae; carpus subrectangular, long, length 2.2 x breadth, longer than (1.6 x) propodus, with patch of very fine setae near posterior margin; propodus small, subtriangular, tapering distally, posterior margin serrate, straight, with 4 simple robust setae, palm absent; dactylus rasp-like. Gnathopod 2: grossly subchelate in female, minutely subchelate in male; coxa large, subequal in size to coxa 3; ischium long, length 2.6 x breadth; carpus long, length 2.8 x breadth, posterior margin straight; propodus subrectangular, short, length 1.7 x breadth, palm transverse, with concave, smooth margin, posterodistal corner without robust setae; dactylus reaching corner of palm, posterior margin smooth.

Peraeopod 3: coxa large; merus-carpus without plumose setae in male and female; propodus with 12 slender setae along posterior margin, with 2 distal locking setae; dactylus short, slender. Peraeopod 4: coxa with large posteroventral lobe, anterior margin slightly rounded, posterior margin slightly sloping anteriorly; merus-carpus without plumose setae in male and female; propodus with 12 slender setae along posterior margin, with 2 distal locking setae; dactylus short, slender. Peraeopod 5: coxa bilobate, posterior lobe slightly produced ventrally; basis expanded with posterior margin minutely crenate; merus slightly expanded posteriorly; propodus with 10 robust setae along anterior margin, with 1 distal locking seta; dactylus short, slender. Peraeopod 6: coxa small, not lobate posteriorly; basis expanded posteriorly with sinusoidal posterior margin; merus slightly expanded posteriorly; propodus with 5 pairs of robust setae along anterior margin, with 1 distal locking seta, with 10 slender setae along posterior margin; dactylus short, slender. Peraeopod 7: basis expanded posteriorly, posterior margin almost straight, minutely crenate, posteroventral corner subquadrate, posteroventral margin sloping inward; merus slightly expanded, convex posterior margin with 4 robust setae; propodus with 6 pairs of robust setae and 2 distallocking setae, with 5 groups of slender setae along posterior margin; dactylus short, slender.

Oostegites: from gnathopod 2 to peraeopod 5. Gills: from gnathopod 2 to peraeopod 6, with strong horizontal pleating.

Pleonites 1 to 3: dorsally smooth. Epimeron 1: anteroventral corner rounded. Epimeron 3: posteroventral corner broadly rounded. Urosomites: dorsally smooth. Uropod 1: with long fine setae; peduncle with 5 dorsolateral, 1 apicolateral, 4 dorsomedial and 1 apicomedial robust setae; rami subequal in length; outer ramus with 7 lateral robust setae; inner ramus with 4 medial robust setae. Uropod 2: with long fine setae; peduncle with 3 dorsolateral, 1 apicolateral and 1 apicomedial robust setae; rami subequal in length; outer ramus with 5 lateral robust setae; inner ramus with 3 lateral and 1 medial robust setae; inner ramus with weak constnctIOn. Uropod 3: peduncle short, length 1.5 x breadth, with dorsolateral flange, with 5 dorsolateral and 2 dorsomedial robust setae, without midlateral slender or robust setae, without distoventral robust setae, without plumose setae in female or male; rami lanceolate, subequal in length; outer ramus 1- articulate, article 1 without robust setae; inner ramus with 3 lateral and 3 medial robust setae; slender plumose setae absent in female and male. Telson : as long as broad, length 1 x breadth, moderately cleft (49%), with 1 dorsal robust seta on each lobe, without dorsal slender setae, distal margins rounded, with 1 marginal penicillate seta on each lobe, without marginal simple setae, with 1 marginal robust setae on each lobe.

Etymology. This species is named for Dr Gary Poore, carcinologist at the Museum of Victoria, in recognition of his exceptional achievements in making known the south-eastern Australian peracaridan fauna.

Remarks. The robust, highly cornified mouthparts of T. poorei suggest a tough diet such as sponges. The non-cuspidate setal-teeth on the outer plate of maxilla 1 are unusual in lysianassoids. According to Dr W. Rudman (pers. comm.) Australian Museum, dorid opisthobranchs which feed on spiculate sponges have no cusps on their teeth whereas chromodorids, which feed on non-spiculate sponges, have cuspidate teeth.

Distribution. Thaumodon poorei is currently known only from Western Port, Victoria, south-eastern Australia.

Figures

Fig. 2. Thaumodon poorei n.gen., n.sp. holotype, female, 14 mm, NMV J25814; whole animal, paratype female, 15 mm, AM P40431; Western Port, Victoria, Australia. Scales represent 0.5 mm.

Fig. 3. Thaumodon poorei n.gen., n.sp. holotype, female, 14 mm, NMV J25814, paratype male, 11.5 mm, NMV 13787, Western Port, Victoria, Australia. Scales represent 0.5 mm.