Mesanthura protei Kensley 1980

Mesanthura protei

MATERIAL.—Holotype: USNM 171713, 1 ovig , TL 8.0 mm, Sta AB 372P. Paratypes: USNM 171714, 1 , TL 5.6 mm, 1 , TL 3.8 mm, 3 juvs; Sta JR 29; USNM 171715, 1 , TL 3.9 mm, 2 ovig , TL 5.5–6.5 mm, 3 , TL 3.6–4.0 mm. Additional material: 4 , Sta JR 29; 1 , Sta JR 20; 2 , Sta JR 30; 2 , 3 juvs, Sta JR 31.

DESCRIPTION.—Body proportions: C<1=2=3<4>5>6>7. Eyes present. Rostrum low. Pleonites 1–5 fused, pleonite 6 free. Telson distally broadly rounded, with few mediodistal setae, and two proximal statocysts. Antennular peduncle with basal segment broadest and longest; fourth segment very short; flagellum of two articles. Antennal peduncle with second segment broadest and longest, third segment short; flagellum of three (possibly four) articles. Mandibular palp 3-segmented, terminal segment with nine spines; incisor of three cusps; lacinia with about eight serrations; molar blunt, somewhat reduced. Maxilla slender, with six terminal spines. Maxilliped 5-segmented, second segment longest, third segment slightly narrower than flanking segments; terminal segment narrower than fourth, with single short plumose seta basally, and three simple setae and one plumose seta mediodistally. Pereopod 1 unguis one-third length of dactylus; propodus broad, palm with rounded setose lobe; carpus triangular, distally rounded. Pereopods 4–7 unguis one-third length of dactylus; propodus with strong ventrodistal spine and five short spinules; carpus short, triangular, with strong ventrodistal sensory spine. Pleopod 1 exopod operculiform, distal margin bearing plumose setae, two and one-half times wider than endopod, subequal in length; basis with five retinaculae. Uropodal exopod with setose margin, barely discernible notch on outer margin; endopod extending slightly beyond telsonic apex.

Male: Eyes well developed, larger than in female. Antennule with brushlike flagellum of 12–14 articles bearing dense whorls of filiform aesthetascs. Pereopod 1 with rounded setose process on palm, as in female, plus numerous short curved spines along entire inner margin of palm. Pleopod 2 with copulatory stylet on endopod extending well beyond ramus, apically rounded. Uropodal exopod slightly smaller than in female.

Pigment Pattern: No distinct pigment pattern can be seen in the males, where the chromatophores are scattered over the dorsal and ventral surfaces of the body. In the females, three pigment patterns can be seen:

1. Strong, almost solid band on cephalon, just posterior to eyes; scattered chromatophores on pereon and pleon.

2. Two irregular longitudinal bands on cephalon, pereon, and pleon, linked anteriorly on pereonites 1–3, linked posteriorly on cephalon and pereonites 4–7.

3. Broad almost solid band across cephalon just posterior to eyes; irregular patch on pereonites and pleon, each patch with unpigmented central medallion.

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