Pyrgoniscus scopelicus, Lillemets & Wilson, 2002

Lillemets, B. & Wilson, G., 2002, Armadillidae (Crustacea: Isopoda) from Lord Howe Island: New Taxa and Biogeography, Records of the Australian Museum 54, pp. 71-98 : 86-90

Pyrgoniscus scopelicus n.sp.

Figs. 12–14

Type material. HOLOTYPE Ƌ, P59946, 10.7 × 6.0 mm, Ball’s Pyramid K &M 24.i.80 . PARATYPES, all from Ball’s Pyramid, K&M 21.i.80 or 24.i.80: P59950 , 14.2 × 8.6 mm.; P59997 , Ƌ, 5 SEM stubs; P59947 , Ƌ; P59949 , Ƌ; P59998, ♀ , 3 SEM stubs, photo K.1037; P59951, 2 ♀♀; P59948, 3 ♀♀ .

Type locality. Ball’s Pyramid (near Lord Howe Island), New South Wales, Australia, 31°46'S 159°16'E, collected under and behind exfoliating rock, crevice in rock face, K&M, 21& 24 January 1980 .

Additional material. P34877, 9 inds; P34878, 27 inds; Ball’s Pyramid, collected under and behind exfoliating rock, crevice in rock face, K&M, 24.i.80.

Diagnosis. Cephalon frontal lamina entire, straight; ridgelike tubercle above each eye. Pereonite 1 dorsal ornamentation with midline tubercles forming a “V” behind anterior margin, area around it smooth, tubercles concentrated in two round “shoulder” areas. Pleonites dorsal surface smooth. Pleotelson hourglass shape; posterior margin straight; single midline ridge distally from level of constriction, not reaching posterior margin. Male pereopod 1 carpus distoventrally with “brush” of setae, increasing in length distally. Uropod protopod length 1.9 width; dorsal surface ridged; endopod 3.0 exopod length.

Description. Colour uniform grey-brown in alcohol. Body ( Fig. 12A,B,G) dorsoventrally flattened with expanded horizontal epimera. Cephalon ( Fig. 12C,D) frontal lamina raised above vertex, uncleft, straight, distal lateral margins triangular; ridge-like tubercle above each eye, row of low,

pleopod 2 and exopod tip, ventral view. Scale bar = 1 mm.

rounded tubercles along posterior margin, scattered low rounded tubercles; head width 2.5–3.0 length. Eyes with 17–20 ocelli in adults. Pereon ( Fig. 12A–C) epimera 1 narrowly rounded anteriorly, lateral margin simple, posterior margin rounded rectangular, dorsal surface concave, ventral surface with longitudinal ridge close to tergite epimera junction extending from anterior margin, ending in toothlike endolobe anterior to posterior margin; epimera 2 anterior margin rectangular, posterior margin rounded rectangular, ventral surface anterior margin thickened, extending in blunt tooth-like endolobe close to tergite junction near midline; epimera 3–7 anterior margins rectangular, decreasingly angled towards posterior, epimera 7 straight; epimera 2–4 posterior margins rounded, that of epimera 5–7 rectangular; epimera 3–7 endolobes absent. Tergites1–6 posterior margins slightly curved, tergite 7 straight; tergite 1 length 0.25 pereon length. Dorsal ornamentation ( Fig. 12A–C) tergite 1 midline tubercles forming a “V” behind anterior margin, area around it smooth, tubercles concentrated in two round “shoulder” areas, rest of tergite with scattered tubercles, narrow band along posterior margin smooth; tergite 2–7 each with row of tubercles, smooth narrow band along posterior margin; epimera 1 with scattered tubercles, epimera 2–7 ridged; tergal cuticle with small scattered scales. Pleon ( Fig. 12F)

pleura 3–5 truncate, ridged; pleonite 1–2 posterior margin straight, pleonite 3–5 slightly curved; endolobes absent; pleonites dorsal surface smooth. Pleotelson ( Fig. 12I) hourglass shape, greater part posterior to constriction, proximal width 0.9 distal width, length 0.9 proximal width; posterior margin straight; two rounded tubercles near anterior margin, midline ridge distally from level of constriction, not reaching posterior margin. Antenna ( Figs. 12C,D, 14L) long, slender, reaching epimera 2 posterior margin; flagellum length 0.6 article 5 length; flagellar articles length proportions 1:2; all segments setose, flagellum with long apical seta. Mandibles ( Fig. 14 A,B,D,E). Right mandible lacinia mobilis base setose lobe with row of long simple setae; left mandible with 6 robust penicils. Maxilliped ( Fig. 14F,G) palp article 2 apical group of setae on small lobe. Male pereopod 1 ( Fig. 14H,I) carpus distoventrally with “brush” of setae, increasing in length distally. Penes ( Fig. 14K) lanceolate; proximal bilobed lamellar process triangular, length 0.4 penes length. Male pleopod 1 ( Fig. 13A,B) exopod triangular, with four separate lateral setae near apex; pseudotrachea along proximal lateral margin, width 0.5 exopod width, length 0.5 exopod length; exopod length 0.35 endopod length. Pleopod 2 exopod length 2.0 width, proximal wide portion length 0.3 exopod length, pseudotrachea along lateral margin, width 0.5 exopod width, length 0.2 exopod length, distolateral row of long, thick setae; endopod proximal article length 0.2 endopod length; exopod length 0.75 endopod length. Pleopods 3–5 exopods ridged near dorsolateral margin, ventral long thick setae along lateral margin of apical half. Uropod ( Fig. 12H,I) protopod length 1.9 width; proximal medial margin straight portion 0.2 protopod length; protopod distally visible dorsally, length 0.67 protopod length; length (along inner margin of dorsally visible portion) 2.0 width (at point of exopod insertion); dorsal surface ridged; exopod inserted dorsally midway to apex, length 0.25 protopod dorsally visible portion length; endopod 3.0 exopod length.

Etymology. Scopelicus means “of a rocky crag projecting from the sea”, a good description of Ball’s Pyramid.

Remarks. We here list all species that have been recorded in Pyrgoniscus and indicate how P. scopelicus n.sp. differs from them. The frontal lamina is lower in P. scopelicus than in P. lanceolatus Ferrara, 1977 and P. petiti Monod, 1935 . The straight frontal lamina differentiates it from P. intermedius Lewis, 1998b (also from Lord Howe Island). Unlike this species, the frontal lamina is cleft in P. cinctutus Verhoeff, 1926 , P. exilis ( Budde-Lund, 1885) , P. translucidus translucidus ( Budde-Lund, 1885) , P. hispida ( Vandel, 1973) , P. canaliculatus ( Budde-Lund, 1904) , P. iniquus ( Budde-Lund, 1904) , P. noduligerus ( Verhoeff, 1926) , P. translucidus gracilio ( Verhoeff, 1926) , P. bicarinatus ( Budde-Lund, 1913) and P. chathamensis ( Budde-Lund, 1885) . Pyrgoniscus carinatus ( Verhoeff, 1926) has a straight sided pleotelson rather than an hourglass shape. A single ridge on the pleotelson separates this species from P. impressifrons ( Budde-Lund, 1904) by a single ridge on the pleotelson, and from P. rugosus ( Budde-Lund, 1913) by differences in dorsal ornamentation (see Fig. 12A,B).