Polyophthalmus mauliola Magalhães & Rizzo & Bailey-Brock 2019, sp. nov.

Polyophthalmus mauliola sp. nov.

Figures 8 (A–F) and 9 (A–E)

Material examined. Holotype: Mamala Bay, Oahu, Hawaii: vicinities of Sand Island outfall, Oct/2015, Sta. D 3AR3, 21°16'55.4" N, 157°53'49.2" W, 50 m (BPBM-R3887); Paratypes: same locality, date as holotype (4 spms, BPBM-R3888). Additional material examined: Sta. D 2R1, 21°16'55.2" N, 157°54'36.6" W, 56.4 m (2 spms); Waianae outfall, May/2015, Sta. W2R6, 21°24'46.5" N, 158°11'45.6" W, 27.7 m (17); Sta. ZWR4, 21°25'25.1" N, 158°11'55.4" W, 34.1 m (2); Sta. W1R1, 21°23'32.5" N, 158°11'27.7" W, 31.7 m (2); Sta. ZER1, 21°25'23.3" N, 158°11'47.5" W, 30.5 m (7). Kaneohe Bay, 8 miles offshore, 30 m, Oct /1982, coll. R. Brock (3); Halape, Big Island, Hawaiian volcano national Park, shallow subtidal (2). About 1 km offshore Waikiki, Sta. SW, Feb /2016, coll. M. Hixon (9).

Diagnosis. Parapodia biramous, chaetae emerging from body wall throughout; minute digitate ventral cirrus; interparapodial ciliated sensorial cilia present anteriorly and forming distinct lobes on last 5–7 chaetigers. Anal tube very short; posterior border with a basal pair of conical papillae, and up to four pairs of short, digitate marginal papillae.

Description. Holotype 7.5 mm long, 0.3 mm wide for 26 chaetigers. Paratypes ranging from 5–8 mm long, 0.3– 0.5 mm wide for up to 28 chaetigers. Body slender, tubular tapering from last five chaetigers with deep ventral and lateral grooves (Figs 8A, B; 9A); lateral groove beginning anterior to chaetiger 1 (Figs 8A, B; 9A, B). Prostomium broadly rounded, palpode absent (Figs 8 A–C; 9A, B). Nuchal organs large, deep oval lateral depressions (Figs 8B, C; 9B). A pair of small reddish eyespots deeply and ventrally embedded in prostomium seen in all specimens and a third and smaller eyespot on dorsal side observed in some specimens (Fig. 8B, C). Pharynx not observed. Holotype preserved pale yellow in color and some paratypes with lightly colored brown rings present on dorsal and lateral region, absent ventrally.

Parapodia biramous, chaetae emerging from body wall throughout; minute digitate ventral cirrus also present throughout; interparapodial ciliated sensorial cilia present throughout half way between notopodia and neuropodia chaetae and forming a distinct lobe on last 5–7 chaetigers (Figs 8 D–F; 9D, E). Simple capillary chaetae in two bundles; 2–3 capillaries per bundle anteriorly reducing to 1–2 posteriorly; notochaetae slightly longer than neurochaetae; additional 3–4 short capillaries per bundle seen only with SEM. Chaetae of last 5–7 posterior chaetigers longer and surpassing pygidium (Figs 8A, E, F; 9E). Smallest individual (1 mm long, 19 chaetigers) with capillaries of last segment very long, almost 1/6 of total body length. Lateral eyespots anterior to parapodia on 11 chaetigers (chaetigers 7–17), reddish brown, rounded; eyespots of chaetiger 7 and chaetiger 17 smaller than others; eyespots on posterior edge of segment.

Anal tube very short, preserved specimens with tapering posterior end (Fig. 8E, F). Posterior border provided with a basal pair of conical papillae, and up to four pairs of short, digitate marginal papillae can be completely retracted (Figs 8E, F; 9E).

Remarks. Table 1 shows morphological features of eight Polyophthalmus species present in the Indian and Pacific oceans, including P. pictus from the Mediterranean for comparison. Polyophthalmus mauliola sp. nov. is unique among all congeners by the presence of a minute, digitate ventral cirri in all segments and enlarged interparapodial ciliated sensory lobes on the very posterior segments. These lobes can be interpreted as interramal papillae because they emerge in between notopodial and neuropodial chaetae that are clearly separated and covered with sensory cilia. The distribution of the segmental eyes from chaetigers 7–17 is similar to what have been reported for P. australis and distinct from P. ceylonensis (ch. 7–15), P. qingdaoensis (ch. 7–18), and P. striatus (ch. 5–16).

The body pigmentation has extensively been used to separate Polyophthalmus species but preserved specimens of P. mauliola sp. nov. have shown some variability from completely unpigmented and translucent to presenting transverse bands across dorsum. This is mostly due to fixation and preservation techniques, so the use of pigmentation to separate species should be done with caution and based on live material, if possible. Kükenthal (1887) presented illustrations of two species with distinct pigmentation, P. ceylonensis and P. striatus. While P. striatus had complete transverse bands of dark brown color across the dorsum along the entire body, P. ceylonensis only showed transverse bands on anterior five segments and patches of dark brown pigments on the dorsum from mid- to posterior segments. Purschke et al. (1995) showed that P. qingaoensis presented pigmented spots on the brain region of the prostomium in addition to dorsal ribbon-like spot of red pigments in most segments of live specimens.

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The structures of the anal cone are also helpful on separating species of this genus. Polyophthalmus mauliola sp. nov. has a short anal cone with a pair of basal and elongate papillae clearly distinct from the eight short and digitate marginal papillae. Polyophthalmus australis and P. striatus were also described with a pair of basal papillae that were larger than eight (P. striatus) or nine (P. australis) marginal papillae; no illustrations were provided for P. australis. Polyophthalmus pictus and P. qingdaoensis lacked distinct basal anal papillae and both species have the dorsal pair of marginal papillae larger than ventral ones; P. qingdaoensis was also described with a dorsal notch on the anal cone.

Etymology. The epithet of this species refers to the Hawaiian term Mauli-ola meaning breath of life, power of healing and also a God of health. Mauliola was also the name of Sand Island, a small island near the type locality of this species in Mamala Bay that was used as a quarantine station in 1869 (also known as Quarantine Island).

Distribution. The type locality is in Mamala Bay, south shore of Oahu, Hawaii. This species has also been collected in Waianae, Kaneohe Bay, Waikiki, Pearl Harbor (Oahu) and Halape (Big Island) from 27–56 m depth in sand and coral rubble.