Dactylopleustinae Bousfield & Hendrycks, 1994, 1979

Dactylopleustinae Bousfield & Hendrycks, 1994 View in CoL

Dactylopleustinae Bousfield & Hendrycks, 1994: 38 View in CoL .— Bousfield & Hendrycks 1995: 119.— Tomikawa et al. 2004: 3.

Type genus. Dactylopleustes Karaman & Barnard, 1979: 112 View in CoL .

Genera. Dactylopleustes Karaman & Barnard, 1979 View in CoL .

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).