Pseudidothea hoplites, Poore And T, 2004

Poore And T, Gary C. B., 2004, Pseudidotheidae (Crustacea: Isopoda: Valvifera) reviewed with description of a new species, first from Australia, Memoirs of Museum Victoria 61 (1), pp. 75-83 : 76-79

Pseudidothea hoplites sp. nov.

Figures 1–3

Material examined. Holotype. Western Bass Strait, 70 km W of Cape Farewell, King Island , Tasmania (39°38.2'S, 143°07.2'E), 127 m, sand, epibenthic sled, R. Wilson on RV Tangaroa , 21 Nov 1981 (stn BSS 195), NMV J8705 (male, 4.4 mm).

Paratypes. Type locality, NMV J8706 (1 female); 36 km SSW of Stokes Point (40°26.7'S, 143°41.4'E), 85 m, rock dredge, 22 Nov 1981 (stn BSS 198), NMV J8709 (1) ; 59 km WNW of Cape Farewell (39°28'S, 143°17'E), 103 m, Smith-McIntyre grab/pipe dredge, G.C.B. Poore on HMAS Kimbla , 10 Oct 1980 (stn BSS 81), NMV J8703 (1).

Victoria, 80 km SSE of Cape Otway (39°26'S, 142°57'E), 113 m, 9 Oct 1980 (stn BSS 67), NMV J8701 (2) ; NMV J23186 (1 ovigerous female, 5.1 mm, figured) ; 51 km SSW of Cape Otway , Victoria (39°16'S, 143°17'E), 90 m, 10 Oct 1980 (stn BSS 73), NMV J8702 (1) ; 45 km SSW of Cape Otway (39°15'S, 143°19'E), 94 m (stn BSS 74), NMV J8704 (2 males); 55 km SW of Cape Otway (39°16.7 ’ S, 143°06.7'E), 95 m, rock dredge, R . Wilson on RV Tangaroa , 21 Nov 1981 (stn BSS 193), NMV J8707 (male, female) ; 44 km SW of Cape Otway (39°06.3'S, 142°55.6'E), 81 m (stn BSS 192), NMV J23077 (1) ; 60 km SW of Cape Otway (39°06.3'S, 142°55.6 ’ E), 84 m, fine shell (stn BSS 191), NMV J8708 (1).

Other material. Tasmania. Breaksea Island, Bathurst Harbour (43°20'S, 145°57'E), 4 m, NMV J23085 (1 ovigerous female, SEM examination) . Isle des Phoques (42°25’S, 148°10 ’ E), NMV J23084 (1) . Bicheno, eastern side of Waubs Bay , reef (41°53 ’ S, 147°18 ’ E), 7 m, Macrocystis holdfasts (stn TAS 94), NMV J23081 (1) ; E side of Waubs Bay , reef local name “Split Rock” (41°53'S, 147°18'E), 11 m, red and brown algae (stn TAS 102), NMV J23083 (2) ; granite reef 50 m offshore, N end of “ The Gulch ” (41°53'S, 147°18'E), 7 m, erect red algae (stn TAS 88), NMV J53071 (1) ; reef close to base of “ Split Rock ” (41°53'S, 147°18'E), 12 m, fine sand from base of reef (stn TAS 96), NMV J23082 (1).

Victoria. “Harry’s Hole”, W side of Twin Reefs, Venus Bay (38°41'S, 145°39'E), 9 m, rocky (stn CPA 8), NMV J23079 (1) . 75 m SW of Eagles Nest (38°40'S, 145°40'E), 8 m (stn CPA 3), NMV J23078 (1) . Off Eagles Nest (38°40.67'S, 145°38.76'E), 10–11 m, mixed algae (stn BUN 3), NMV J53073 (1) . Aireys Inlet (38°28'S, 144°06'E), from Sphacelaria, NMV J 23080 (1) .

Diagnosis. Head dorsally strongly elevated, with paired double or single spines. Pereonite 1 with 1 pair of small dorsal spines, 2 small lateral spines. Tergites 2–7 each produced laterally in form of a with 3 points, anteriorly, posteriorly and laterally. Pereonites 2 and 3 with small paired middorsal spines, large paired dorsolateral forked spines, and lateral ridges produced acutely anteriorly and posteriorly; pereonites 4–7 with dorsolateral and lateral ridges, each produced acutely anteriorly and posteriorly, and several anterodorsal and posterodorsal spines. Pleotelson with anterolateral processes, paired anterodorsal convexities, a series of 3 spines on each side (dorsal–lateral) and pair of mediodorsal convexities, remaining pleotelson tapers to an obtuse apex.

Male antenna 1 flagellum with 6 clusters of aesthetascs. Antennae and pereopods with tubercles. Antenna 2 with short setae on articles 3–5. Male pleopod 1 endopod about 1.5 times as long as peduncle with plumose setae apically; exopod longer, 8 spinules on lateral margin, tapering distally, thickened and folded laterally to partially cover a groove that runs to the apex. Male pleopod 2 appendix masculina styliform, slightly longer than endopod. Uropodal exopod about two-thirds as long as endopod; exopod with a strong apical seta; endopod with 3 brush setae and 2 setules. Oostegite absent from pereopod 5.

Description. Ornamentation. Head dorsally strongly ele-vated, with paired double or single spines. Eyes prominent, arising laterally. Lateral margin of head armed with about 7 small teeth, extending downwards and outwards. Head fused to pereonite 1, partial suture visible laterally. Pereonite 1 with pair of small dorsal spines, 2 small lateral spines, lateral margin with about four small teeth. Tergites 2–7 produced laterally to form a shield with 3 spines, laterally, anteriorly and posteriorly. Pereonites 2 and 3 with small paired dorsal spines, large paired dorsolateral forked spines, and lateral ridges finished anteriorly and posteriorly with a small spine. Pereonite 4–7 with dorsolateral and lateral ridges, finished anteriorly and posteriorly with a small spine. Pereonite 4 with 4 anterodorsal and posterodorsal spines, pereonites 5 and 6 with 3 and pereonite 7 with 2 and a single dorsal denticle.

Sculpture of pleotelson from anterior to posterior as follows. A central pair of dorsal convexities each with an anteriorly directed spine, lateral to these a series of 3 anteriorly directed spines on each side, followed by large lateral convexities on each side, followed by a pair of central dorsal convexities, remaining pleotelson tapers to an obtuse apex.

Antennae, mouthparts and limbs (from male). Antenna 1 peduncle articles with brush setae, articles rounded and becoming successively smaller; flagellum article 1 very short; article 2 with 6 aesthetascs and setules. Antenna 2 peduncle articles 3–5 with blunt tubercles on lower margin, bearing robust setae, especially on articles 4 and 5; flagellum almost as long as peduncle article 5, articles becoming successively smaller, first with distal robust seta and setules, second with setules, third a short claw.

Mandible incisor with 4 uneven teeth; left lacinia mobilis almost as wide as incisor, with 3 teeth; right lacinia mobilis an unevenly toothed column; left molar process with concave face rimmed by obscure teeth and bearing a setal cluster; right molar process with face ending with row of blunt teeth and bearing setal cluster. Maxilla 1 inner lobe with 2 long pappose setae; outer lobe with 11 apical setae, some obscurely dentate. Maxilla 2 inner lobe oblique margin with 6 pappose setae along posterior edge, 5 setae on anterior edge; middle lobe with 2 longer pappose setae; outer lobe with 3. Maxilliped endite with complex of thin pappose setae and rows of blunt tubercles; palp with tubercles and long setae on mesial margins of articles 2–5; articles 1 and 2 short, 3 and 4 of subequal length, 3 produced mesially, article 5 one-fifth as long as 4, almost as long as wide; epipod apex with small blunt tooth.

Pereopod 1 held close to the mouthparts; merus–propodus with uneven posterior tubercles and stout pectinate setae; propodus almost as wide as long, with rows of mesial pectinate setae along anterodistal margin; proximal part of dactylus linear, about 2.5 times as long as greatest width, complexly setose with mesial pectinate setae, 1 spinule on posterior margin, posterodistal corner of dactylus with a spinule, seta and 2 setules; unguis a strong claw, less than half length of dactylus.

Pereopod 2 basis–merus short, subequal, carpus–dactylus longer; merus with complex tubercle on lower margin bearing short setae; carpus longer than greatest width, with tubeculate ridge on lower margin bearing 2 long robust setae; propodus robust, about twice as long as wide, with 2 robust setae on lower margin opposing carpus; proximal part of dactylus almost 3 times as long as wide, unguis a short claw. Pereopod 3 similar to pereopod 2. Pereopods 4–7 basis–merus with blunt tubercles on upper margin, most articles with well spaced setae on lower margin; basis about 1.5 times as long as wide; ischiumcarpus subequal, about as wide as long; propodus about 2.5 times as long as wide, dactylus similar to pereopod 2.

Male pleopod 1 peduncle twice as long as wide, with 4 coupling hooks; endopod lamellar with 6 apical plumose setae; exopod longer than endopod with 8 spinules on lateral margin, tapering distally, thickened and folded laterally to partially cover a groove that runs to the apex. Male pleopod 2 rami apically flattened, endopod with 9 apical plumose setae; exopod with 21 marginal plumose setae; appendix masculina styliform, slightly longer than endopod. Pleopods 3–5 becoming successively larger, rami apically rounded with single simple seta on endopod.

Uropod unarmed, rounded anteriorly, tapering posteriorly; exopod about two-thirds as long as endopod, conical, with apical seta; endopod broader, apically rounded with 4 distal setae and 3 lateral setae.

Sexual differentiation. Female differs from male in broader body, especially of pereonites 2–4; ornamentation more developed; antenna 1 flagellum with 3 clusters of aesthetascs on article 2; pereopods 1–4 with oostegites, pereopod 5 without oostegite; penial process absent; pleopods 1 and 2 without male modifications. Male with ventral terga separate on pereonites 1–4 and fused across midline of pereonites 5–7.

Etymology. Hoplites (Gr.) , man in armour, in reference to the elaborate spines and ridges.

Distribution. South-eastern Australia (Victoria and Tasmania), 4–127 m depth.

Remarks. Pseudidothea hoplites is distinguished from other species of Pseudidothea by the complex ornamentation of the pereon comprising forked projections on pereonites 2 and 3, and dorsolateral and lateral lobes produced front and back. It is most similar to P. richardsoni from New Zealand but is much more ornamented. The lateral projections of pereonites 2 and 3 are more exaggerated but both species have anterior and posterior spines.