Syrrhoe petitaserrata, Hughes, 2009

Hughes, L. E., 2009, Synopiidae *, Zootaxa 2260 (1), pp. 880-891 : 884-887

Syrrhoe petitaserrata sp. nov.

( Figs 3 , 4 )

Type material. Holotype, female 3.4 mm, 3 slides, AM P77880, off Osprey Island , Lizard Island area (14°40'S 145°26'E), surface plankton tow, full moon, J.M. Leis, 7 October 1979, ( JML 7-10 - 1 ) . Paratypes: 6 specimens, AM P77885 (same locality) .

Additional material examined. 1 unsexed specimen, AM P77886 ( JML 17-10-2); 3 unsexed specimens, AM P77887 ( QLD 16); 2 unsexed specimens, AM P77881 ( QLD 21); 1 unsexed specimen, AM P28474 ( QLD 28); 1 unsexed specimen, AM P28476 ( QLD 29); 1 unsexed specimen, AM P28477 ( QLD 30); 2 unsexed specimens, AM P77884 ( QLD 1907); 1 unsexed specimen, AM P77883 ( QLD 1981); 1 unsexed specimen, AM P77882 ( QLD 1983).

Type locality. Off Osprey Island , Lizard Island area (14°40'S 145°26'E) .

Etymology. From petite – ‘small’; and serrata – ‘serrate,’ referring to the smaller size of the species in comparison to other closely related Syrrhoe species.

Description. Based on female, 3.4 mm, AM P77880.

Head. Head protuberant; rostrum short, apically acute; lateral cephalic lobe absent; eyes less than half length of the head; accessory eyes absent. Antenna 1 peduncular article 1 not elongate, with a distal tooth; peduncular article 2 not elongate; flagellum shorter than pereon, 6–articulate. Antenna 2 flagellum 8– articulate. Mandible palp article 2 with many slender setae; article 3 with many slender apical setae; molar greatly enlarged, smooth, not triturative, accessory setal row with 2 serrate setae. Maxilla 1 inner plate with 5 slender setae. Maxilliped not foliaceaous.

Pereon. Pereonites 6–7 without lateral ridge. Pereonite 7 without carination. Gnathopod 1 subchelate; coxa anterior margin not produced, not tapering distally; basis longer than carpus; propodus palm acute, defined by serrate robust seta. Gnathopod 2 subchelate; coxa not distally tapering; basis longer than carpus; propodus palm acute, defined by serrate robust seta; dactylus well developed. Pereopod 3 coxa anterodistal lobe produced subacute, posterodistal lobe margin smooth, truncate, greater than half depth of coxa. Pereopod 4 coxa smaller than coxa 3, lobate in shape, with weakly developed posteroventral lobate. Pereopods 5–7 basis anterodistal corner produced rounded, posterior margin serrate. Pereopods 5–6 basis subovoid, expanded, posterodistal lobe well developed, acute, extending below ischium. Pereopod 7 basis ovate, posterodistal lobe well developed, acute, extending below ischium.

Pleon. Pleonites 1–3 without lateral ridges. Pleonites 1–2 posterodorsal margin smooth. Pleonites 1–2 carinate. Pleonite 3 without carination; posterodorsal margin smooth. Epimeron 1 posterior margin smooth, posterodistal corner acute. Epimeron 2 posterior margin smooth, posterodistal corner produced acute. Epimeron 3 posterior margin serrate distally. Uropod 3 length not exceeding uropods 1–2; peduncle short (less than 2 x breadth). Telson deeply cleft, longer than uropod 3 peduncle, without setae along the lateral margin, with single pair of slender apical setae.

Habitat. Mixed algae and coral rubble, 6–27 m depth, nektonic at night.

Remarks. The new species, Syrrhoe petitaserrata , is most similar to S. semiserrata Stebbing, 1888 , described from off Melbourne, in south-eastern Australia. These species have no dorsal serrations on the pereon or pleon and epimeron 3 is distally serrate. This combination of characters separates them from all other Syrrhoe species except S. serrima J.L. Barnard, 1972 . Eyes are present in S. petitaserrata sp. nov. and S. semiserrata but are absent in S. serrima . The lobes of the telson in the former two species abut along the cleft inner margin, where in S. serrima the telsonic lobes are divergent.

In S. petitaserrata pereopods 5–7 are shorter in length in relation to the body compared to those of S. semiserrata . On pereopods 5–7 the serrations on the basis posterior margin are more pronounced those of S. petitaserrata . The apical margins of the telson are acute in S. petitaserrata and truncate in S. semiserrata . Syrrhoe petitaserrata s can be further distinguished from S. semiserrata by the fewer number of plumose setae on the maxilla 1 inner plate (5 setae), the smooth mandibular molar, the gnathopod 1 carpus length which is shorter than the basis and posterodistal corners of epimera 2–3 which are more acutely produced.

Distribution. Australia. Queensland: Torres Strait; Lizard Island; One Tree Island (current study).

Figures

FIGURE 3. Syrrhoe petitaserrata sp. nov., holotype, female, 3.4 mm, AM P77880, Osprey Island, Great Barrier Reef.

FIGURE 4. Syrrhoe petitaserrata sp. nov., holotype, female, 3.4 mm, AM P77880, Osprey Island, Great Barrier Reef.