Paradella tiffany, Bruce, Niel L. & Wetzer, Regina, 2004

Bruce, Niel L. & Wetzer, Regina, 2004, Paradella tiffany sp. nov., a distinctive sphaeromatid isopod (Crustacea: Isopoda: Sphaeromatidea) from Baja California, Mexico, Zootaxa 623, pp. 1-12 : 3-11

Paradella tiffany sp. nov.

Material examined.— All material from Pacific Mexico. Holotype, ɗ (5.4 mm), Boca del Alamo, Bahia de los Muertos, Baja California Sur, Gulf of California, 23°53.253'N, 109°47.775'W, 10 January 2000, beneath large rounded stones in high intertidal, RW00.104, coll. T. A. Haney ( LACM CR 2000­030.1). Paratypes: Immature ɗ (2.5 mm), 2 non­ovigerous Ψ (2.4, 2.8 mm), same data as holotype, RW00.104 ( LACM 2000­030.2).

Additional material: adult ɗ (4.2 mm), Ψ (2.4 mm), immature ɗ (3.6 mm), Boca del Alamo (local signage reads "Boca de Amo"), Bahía de los Muertos, Baja California Sur, Gulf of California, 23.895°N 109.803°W, 7 October 2003, from beneath rocks in high intertidal, under those with thin coverage of Ulva , UC Mexus station 29, RW03.285, coll. T. A. Haney ( LACM CR 2003­009.1).

Description.— Male. Body about 1.8 times as long as greatest width, strongly vaulted, lateral margins subparallel, widest at pereonite 6; dorsal surfaces smooth. Head anterior margin with single prominent transverse ridge, ventral rostral process weakly developed. Head and pereonite 1 subequal in length, pereonite 1 about 1.5 times as long as pereonite 2, unornamented; pereonites 2<3<4<5<6>7; posterior margins of pereonite 5 and 6 with weak transverse submarginal dorsal ridge; pereonite 7 posterior margin posteriorly produced into flat, posteriorly bifid process, with sinuate lateral margins. Pereonite 7 posteriorly bifid process concealing pleon in dorsal view ( Figure 1 B). Coxae without evident sutures, progressively increasing in size posteriorly, those of pereonite 7 enlarged forming two large posteriorly directed plate­like blades. Pleon with evident sutures and sublateral ‘keys’; lateral margins each with extended flat, upturned, distally rounded lobes. Pleotelson with 6 prominent nodules set as transverse row of 4 and 2; pleotelson sinus conforming to generic diagnoses.

Antennule peduncle article 1 1.8 times as long as wide, about 1.9 times as long as article 2; posterior margin of both articles 1 and 2 with brush­tipped sensory setae; article 3 about 1.1 (1.14) times as long as article 2, 0.6 times as long as article 1, 3.7 times as long as wide; flagellum 9­articled, extending to posterior of pereonite 1, about 3.0 times as long article 3. Antenna peduncle articles 1–3 short, subequal in length, article 1 anterior margin with mass of setae; article 4 about 1.5 times as long as article 3, about 0.7 as long as article 5, articles collinear; flagellum 1.4 times as long as peduncle, extending to pereonite 4, with 14 articles.

Epistome anteriorly truncate, without lateral constriction. Right mandible incisor with 4 cusps, spine row of 2 broad­based multidigitate spines, 1 bluntly serrate and 2 serrate spines; molar process round; palp article 2 0.7 times as long as article 1, distolateral margin with 5 biserrate setae, becoming progressively longer distally; article 3 with 10 serrate setae, terminal seta being largest. Maxillule mesial lobe with 3 long, strongly pectinate RS and 2 shorter simple RS, lateral lobe with 11 peripheral RS on gnathal surface, twelfth seta set between these; 2 proximomesial RS weakly and bluntly serrate, distolateral RS smooth. Maxilla lateral lobe and middle lobe each with 4 curved nodular and finely serrate RS, mesial lobe with 8 serrate and biserrate RS. Maxilliped endite lateral margin sinuate, distal margin with 1 simple acute RS at sublateral angle, 3 blunt simple RS and 5 CP RS; longitudinal row of 4 toothed scales lateral to coupling hook; palp article 2–4 weakly lobed; articles 2–5 with about 13, 13, 8 and 7 setae respectively.

Pereopod 1 robust, basis about 2.1 times as long as greatest width, approximately 3 times as long as propodus; proximal superior margin with few scale­setae; ischium 0.8 times as long as propodus, twice as long as greatest width, superior margin with 1 proximal and one mid­distal acute short simple RS, distal superior margin with distinct spinelike scales, distal inferior margin with short setulose fringe; merus about 0.4 as long as ischium, 0.8 times as long as greatest width, superior distal angle with 2 acute simple RS, inferior margin heavily scaled, with dense setulose fringe, inferior distal angle with 2 simple setae; carpus approximately as long as wide, inferior margin 0.8 times as long as merus, heavily scaled, with dense setulose fringe, inferior distal angle with 2 simple setae; propodus 2.0 times as long as greatest width, inferior margin with prominent scales, distal angle with 1 simple and 1 serrate RS; dactylus 0.6 times as long as propodus, unguis inferior margin with prominent serrate cuticular scales, secondary unguis recurved simple. Pereopods 2 and 3 elongate and slender to pereopod 1. Pereopod 2 basis 3.3 times as long as greatest width, inferodistal angle with single simple seta, superior margin with 3 widely spaced palmate setae; ischium as long as basis, 3.8 times as long as greatest width, superior distal margin with single acute RS at mid­point, inferior margin with 2 short simple setae, distal angle with 1 short simple seta; merus 0.5 times as long as ischium, distal half of inferior margin setulose fringe, with 3 distal simple setae superior distal angle with 2 short, simple setae; 1 palmate seta, inferior margin setulose with 8 widely­spaced simple setae; carpus 1.1 times as long as merus, 3.1 times as long as wide, anterodistal angle with single palmate seta, inferior margin setulose, with 8 simple setae; propodus 0.8 times as long as ischium, 4.2 times as long as wide, superior distal angle with 2 setae, inferior margin setulose, with 4 simple setae. Pereopods 5–7 similar, longer than pereopods 2 and 3. Pereopod 7 basis 3.6 times as long as greatest width, inferodistal angle with 2 simple setae, superior margin heavily scaled, with 3 widely­spaced small sensory palmate seta; ischium 0.8 times as long as basis, 2.7 times as long as greatest width, superior margin with prominent scales, with 1 short proximal and 1 prominent acute RS at midlength, inferior distal angle with 1 short acute RS; merus 0.5 times as long as ischium, 1.6 times as long as wide, superior distal margin with 4 long simple setae, inferior margin setulose with 1 simple seta and several short setae; carpus 0.9 times as long as merus, 1.5 times as long as wide, anterodistal angle with 6 serrate and biserrate RS, inferior margin setulose, inferodistal margin with 1 biserrate and 1 simple RS; propodus 0.8 times as long as ischium, 4.1 times as long as wide, superior distal angle with 7 setae, inferior margin finely setulose, with 4 simple setae; dactylus 0.4 as long as propodus.

Penial processes 4.7 as long as basal width, 10.4 times as long as individual width at point of fusion, distally acute; fused along basal 0.17 of length, sperm duct fused at basal 0.04 of length.

Pleopod 1 exopod and endopod with 32 and 27 PMS respectively; endopod 0.9 as long as exopod, 2.3 times as long as greatest width, proximal lateral margin weakly concave, with distinct heel; distalmost setae of the form of RS; exopod with oblique axis, distal margin subtruncate; peduncle medial margin with 3 coupling hooks. Pleopod 2 exopod and endopod with 35 and 28 PMS respectively; appendix masculina 23 times as long as basal width, 1.8 times as long as endopod, apex narrowly rounded, endopod mesial margin straight, lateral margin weakly convex, proximomedial margin with prominent posteriorly directed lobe; exopod 0.9 times as long as endopod, distal margin subtruncate. Pleopod 3 exopod and endopod with 17 and 15 PMS respectively. Pleopod 4 both rami with prominent thick ridges; endopod distal mesial angle with prominent excision, proximomedial lobe present; exopod lateral margin with c. 12 fine simple setae. Pleopod 5 both rami with prominent thick ridges; exopod with 3 scale patches, 2 distal and 1 proximal to suture, lateral margin with ~14 short simple setae, distal margins with longer scale­setae; endopod with scale­setae on distal margin only. Uropod rami subequal in length, distal margins crenate; endopod broadly rounded, 2.8 times as long as wide, mesial and lateral margins upturned, proximal lateral margin with laterally directed spur; endopod lateral margin convex.

Female. Body shape similar to that of male, pereonite 7 posterior margin lacking posteriorly directed process. Pleon with medial portion indistinctly raised and thickened. Pleotelson with 6 irregular nodules arranged in two transverse rows, the lateral nodules being weak. Posterior margin of pleotelson with medial, vertical, ventrally open, narrow slit, dorsally overridden by bluntly rounded lobe. Uropod rami subequal in length, not extending beyond posterior margin of pleotelson; both rami distally rounded, margins crenate. Brood pouch structure not known.

Remarks: No species of Paradella has been described in which the male has a huge, flat and distally bifid process on pereonite 7. Further identifying characters include the large posteriorly expanded coxae on pereonite 7, the large and broadly rounded uropods which extend well past the posterior margin of the pleotelson, the endopods of which have strongly raised margins giving a bowl­like appearance, and the pleotelson dorsum having four distinct acute sub­medial nodules and two weak lateral nodules. Females can be identified by having two pairs of sub­medial nodules on the dorsum of the pleotelson, these being laterally flanked by weak and poorly defined nodules. The male is further characterised by two apparently unique characters: the plumose marginal setae on the distal margins of the endopod of pleopod 1 are short, stout and formed much as robust setae other than that they are plumose; the lateral margins of the pleon are extended forming a dorsally bent and flat lobe.

In the East Pacific Paradella is represented by P. bakeri ( Menzies, 1962b) from Chile, P. s e t o s a Glynn, 1968 from Pacific Panama and P. dianae ( Menzies, 1962a) from Baja California (type locality) which is also known from numerous localities around the world where it has been introduced (e.g. Bey et al. 2001; Hass & Knott 1998; Javed & Ahmed 1987). Adult males of all these species lack a process on pereonite 7 and lack the large, broadly rounded and bowl­shaped uropods that extend well beyond the posterior of the pleotelson. Most species, including at least one undescribed species from Baja California, have the uropods narrowly rounded or terminally acute.

The genus Dynoides Barnard, 1914 is represented in the East Pacific, including Mexico, by several species ( Carvacho & Haasmann 1984; Espinosa­Pérez & Hendrickx 2002), two of which have prominent posteriorly directed processes. Species of Dynoides are easily distinguished from Paradella tiffany by the processes being rounded in cross­section rather than flat and arising on the pleon, not pereonite 7. The genus Dynoides is otherwise abundantly distinct from Paradella .

Etymology: This species is named for the Tiffany & Company, recognising their support of the Natural History Museum of Los Angeles County (noun in apposition).

Figures

FIGURE 1. Paradella tiffany sp. nov. Holotype. A, lateral view; B, dorsal view; C, frons and anterior of head in ventral view; D, pleotelson, posterior margin, ventral view; E, pleotelson sinus, posterior view; F, pleon and pleotelson, perpendicular view; G, antennule; H, antenna.