Dactylopleustes Karaman & Barnard 1979

Dactylopleustinae Bousfield & Hendrycks, 1994 Dactylopleustinae Bousfield & Hendrycks, 1994: 38.— Bousfield & Hendrycks 1995: 119.— Tomikawa et al. 2004: 3. Type genus. Dactylopleustes Karaman & Barnard, 1979: 112. Genera. Dactylopleustes Karaman & Barnard, 1979. Diagnosis (from Bousfield & Hendrycks 1994, 1995 with additions). Body small, smooth, deep-plated. Urosomite 2 not occluded dorsally. Rostrum short. Eyes large, reniform. Antenna 1 short, pediform or subpediform. Accessory flagellum minute, one-articulate, scale-form. Upper lip: notch shallow, lobes only slightly or not asymmetrical. Lower lip with/without deep, distinct inner lobes. Mandibular molar small, rounded, non-triturative; right lacinia absent; palp article 2 short or not, article 3 without baso-facial A-setae. Maxilla 1: outer plate short, broad, with 11–30 apical strong pectinate setae (spine-like setae); inner plate with single apical seta; palp large, terminal article broad. Maxilla 2: plates short, subequal, inner plate with/without single stout seta along inner margin. Maxilliped: both plates short, weakly armed; palp articles short, article 4 pectinate. Coxal plates 1–4 deep, coxa 1 shortest. Coxal gills medium, sac-like on pereopods 2–4, plate-like on pereopods 5–6, lacking on pereopod 7. Gnathopods 1 and 2 small, slender, weakly subchelate: carpus and propodus elongate, longer in gnathopod 2; palmar margins short, lacking medial tooth, posterior margin variously setose; dactylus short, stout, as long as or overlapping palm. Pereopods 3–7 short; carpus and propodus with numerous short spine-like setae posteriorly in pereopods 3, 4 and anteriorly in pereopods 5–7; dactylus short, inner margin finely crenulate or pectinate. Pereopods 5 regularly homopodous; coxal plate regularly or strongly posterolobate; basis broad. Epimeral plates regular, unmodified. Uropod 1: rami subequal, broad-lanceolate. Uropods 2 and 3: rami unequal, outer ramus broad-lanceolate, the shorter than inner. Telson keeled proximally, apex rounded. Distribution. Marine waters of boreal Pacific. Remarks. Subfamily Dactylopleustinae is a monotypic taxon consisting of the genus Dactylopleustes only. Bousfield & Hendrycks (1994) showed the subfamily Dactylopleustinae to be related to the subfamilies Pleustinae Buchholz, 1874 and Pleusirinae Bousfield & Hendrycks, 1994, based on cladistic analysis. The subfamily Dactylopleustinae differs from the subfamily Pleustinae in the structures of rounded and non-triturative mandibular molar (columnar and triturative in Pleustinae) and maxilla 1 outer plate with 11–30 pectinate apical setae (9 pectinate setae in Pleustinae). The subfamily Dactylopleustinae differs from the subfamily Pleusirinae in the structures of maxilla 1 outer plate with 11–30 pectinate apical setae, inner plate with single apical seta (outer plate with 9 pectinate setae, inner plate without setae in Pleusirinae), and in the structure of gnathopods 1 and 2. According to the listed characteristics, the subfamily Dactylopleustinae is remote from Pleustinae and Pleusirinae. Bousfield & Hendrycks (1995) brought subfamily Dactylopleustinae closer together with the genus Parapleustes Buchholz, 1874 (subfamily Parapleustinae Bousfield & Hendrycks, 1994) based on the non-triturative molar of mandible and ordinary form of maxilliped. In my opinion, the genus Dactylopleustes is most similar in morphology to a genus Chromopleustes Bousfield & Hendrycks, 1995 (subfamily Parapleustinae), on the non-triturative molar of mandible, numerous pectinate apical setae on the outer plate of maxilla 1, ordinary form of maxilliped (outer plate with a few strong apical setae), and the shapes of gnathopods 1 and 2 (with elongate carpus and propodus). Thus, the subfamily Dactylopleustinae shares a common ancestor with the subfamily Parapleustinae. Species of the genus Dactylopleustes have peculiar antenna 1, mouthparts, gnathopods and pereopods specialized for commensal life clinging to globular sea urchins of the genus Strongylocentrotus Brandt, 1835 (Tzvetkova 1975; Bousfield & Hendrycks 1994, 1995). These characters, as well as the peculiar mixture of plesiomorphic and apomorphic features, confirm the allocation of the genus Dactylopleustes Karaman & Barnard, 1979 to a separate subfamily status of Dactylopleustinae (Bousfield & Hendrycks 1994, 1995).