Philine baxteri Valdés, Cadien & Gosliner, 2016, sp. nov.

Philine baxteri sp. nov.

Figures 15–17

Type material. HOLOTYPE: Northeast corner of Shemya Island, Aleutian Islands, Alaska (52º42.85’N, 174º08.06’E), 0 m depth, 30 Aug 1971, 2 mm preserved length, leg. O’Clair (LACM 3435).

Other material examined. BERING SEA: Golovin Bay, Alaska (64º23’N, 162º52’W), 8–19 m depth, 3 shells, 3–3.8 mm long, leg. Baxter (LACM 68-236.6). St Paul Island, Pribilof Islands, Alaska (57º13.05’N, 169º59.76’W), 42 m depth, 4 Sep 1985, 18 shells with dried soft parts, 2.9–3.1 mm long, leg. Baxter (LACM 85- 168.3).

GULF OF ALASKA: Orca Inlet, east of Hawkins Island, Prince William Sound, Alaska (60º31’N, 145º52’W), 46–73 m depth, 1966, 5 shells with dried soft parts, 1.2–1.5 mm long, leg. Baxter (LACM 66-262.18). Cohen Island, east shore of Kachemak Bay, Alaska (59º32.5’N, 151º28.5’W), 2 m depth, Nov 1959, 9 shells with dried soft parts, 2.1–3 mm long, leg. Baxter (LACM 59-23.32). West end of Yukon Island, Kachemak Bay, Kenai Peninsula, Alaska (59º31.5’N, 151º29.5’W), 1 Aug 1973, 3 shells with dried soft parts, 2–2.9 mm long, leg. McLean & Baxter (LACM 73-22.28). Northeast side of Hesketh Island, 0.5 miles southwest of Yukon Island, Kachemak Bay, Alaska (59º30.5’N, 151º31.95’W), 0–1 m depth, 8 Sep 1983, 11 shells with dried soft parts, 1.5– 2.1 mm long, leg. Baxter (LACM 83-113.25). Off north side of Hesketh Island, Kachemak Bay, Kenai Peninsula, Alaska (59º30.5’N, 151º31.0’W), 9 m depth, 2 Aug 1973, 1 shell, 2.9 mm long, leg. McLean & Baxter (LACM 73- 23.40). Kasitsna Bay, north coast of Kenai Peninsula, Kachemak Bay, Alaska (59º29’N, 151º36’W), 0–46 m depth, 1 shell, 2.7 mm long, leg. Baxter (LACM 57-12.82). Outer Herring Island, south of Yukon Island, south side of Kachemak Bay, Alaska (59º29’N, 151º30’W), 0–1.4 m depth, 23 May 1986, 4 shells with dried soft parts, 1.8–3 mm long, leg. Baxter (LACM 86-284.9). West entrance to Seldovia Bay, north side of Kenai Peninsula, Kachemak Bay, Alaska (59º28’N, 151º43’W), 0–2 m depth, Aug 1980, 1 shell, 2.3 mm long, leg. Baxter (LACM 80-71.27). Coal Cove, Port Graham, northwest coast of Kenai Peninsula, Kachemak Bay, Alaska (59º24’N, 151º52’W), 0–2 m depth, Aug 1979, 1 shell with dried soft parts, 2 mm long, leg. Baxter (LACM 79-116.30). Long Island, Tonsina Bay, north coast of Kenai Peninsula, Kachemak Bay, 0 m depth, 12 Jul 1983, 1 shell with dried soft parts, 1.8 mm long, leg. Baxter (LACM 83-62.16). Koyuktolik Bay, southwest of Kenai Peninsula, Cook Inlet, Alaska (59º14.32’N, 151º51.77’W), 0 m depth, 21 Aug 1983, 1 shell with dried soft parts, 2 mm long, leg. Baxter (LACM 83-103.8). Rocky Bay Point, south coast of Kenai Peninsula, Alaska (59º13’N, 151º17’W), 0 m depth, Sep 1980, 1 shell with dried soft parts, 2 mm long, leg. Baxter (LACM 80-75.41). South of Dry Bay, west of Cape Fairweather, Alaska (58º46.01’N, 138º34.66’W), 112 m depth, 11 Aug 1987, 1 shell, 2.9 mm long, leg. Baxter (LACM 87- 339.11). Northeast side of Monashka Bay, near Kodiak, Kodiak Island, Alaska (57º49.9’N, 152º21.7’W), 15–16 Aug 1973, 2 shells, 2.1–2.5 mm long, leg. McLean (LACM 73-32.23). Off northeast side of Kulchkof Island, near Kodiak, Kodiak Island, Alaska (57º46.5’N, 152º22.8’W), 9 m depth, 14 Aug 1973 12 shells, 1.2–2.5 mm long, leg. McLean, Powell (LACM 73-31.34). Approximately 2 miles southwest of Kodiak in St. Paul Harbor, Kodiak Island, Alaska (57º46.3’N, 152º27.2’W), 6–12 m depth, 15 Aug 1973, 16 shells with dried soft parts, 1.1–3 mm long, leg. McLean & Powell (LACM 73-33.29). 3.2 km southwest of St. Paul Harbor, northeast end of Kodiak Island, Alaska (57º46.3’N, 152º27.2’W), 6–12 m depth, May 1961, 1 shell with dried soft parts, 2.5 mm long, leg. Baxter (LACM 61-158.6). Southeast of Biorka Island, Baranof Island, Alaska (56º11.12’N, 135º29.54’W), 249 m depth, 24 Aug 1987, 5 shells, 2.2–3.8 mm long, leg. Baxter (LACM 87-362.5).

AULETIAN ISLANDS: Off Krenitzin Island, Aleutian Islands (54º17’N, 165º46’W), 56 fathoms, 1 Dec 1965, 2 shells 3–3.8 mm long, leg. Quayle (LACM 65-73.5). Makushin Bay, northwest side of Unalaska, Aleutian Islands, Alaska (53º46.16’N, 166º58.83’W), 18 m depth, 20 Sep 1986, 1 shell with dried soft parts, destroyed (LACM 86-301.5). Northwest of Gibson Island, off the northeast side of Attu Island, Alaska (52º57.50’N, 173º14.20’E), 88 m depth, 27 Aug 1986, 1 shell, 3.9 mm long, leg. Baxter (LACM 86-312.7). Middle Rocks, Chicagof Harbor, Attu Island, Aleutian Islands, Alaska (52º56.4’N, 173º15.9’E), 7 m depth, 23 Jul 1979, 1 shell, 1.1 mm long (LACM 79-71.13). Northeast corner of Shemya Island, Aleutian Islands, Alaska (52º42.85’N, 174º08.06’E), 0 m depth, 30 Aug 1971, 1 specimen 5 mm preserved length, dissected, leg. O’Clair (LACM 71- 253.3). Southwest of Ingenstrem Rocks, east of Agattu Island, Aleutian Islands, Alaska (52º30.151’N, 174º14.50’E), 112 m depth, 23 Aug 1986, 1 shell with dried soft parts, 3.7 mm long, leg. Baxter (LACM 86-306.5). North end of Kiska Island, Rat Islands, Aleutian Islands, Alaska (52º04.46’N, 177º41.75’E), 82 m depth, 29 Aug 1986, 4 shells with dried soft parts, 2–2.6 mm long, leg. Baxter (LACM 86-315.4). Vega Point, Kiska Island, Rat Islands, Aleutian Islands, Alaska (51º45.80’N, 177º21.33’E), 148 m depth, 20 Aug 1986, 1 shell, 3 mm long, leg. Baxter (LACM 86-354.8). Banjo Point, Amchitka Island, Aleutian Islands, Alaska (51º28.8’N, 179º08.3’E), 6–20 Aug 1971, 1 shell, 1.9 mm long (LACM 71-251.4).

Description. Live animals unknown. Preserved specimens to 5 mm preserved length, about twice as long as wide (Fig. 15 A). Cephalic shield short, rounded posteriorly. Parapodia short and thick. Shell internal, occupying the entire posterior shield. Shell to 3.7 mm long, bulloid, elongate (Figs. 15 B–E, 16A–B). Aperture broad; spire short, well-formed in some specimens (Figs. 16 A–B). Sculpture composed of conspicuous spiral lines, formed by partially fused punctuations. Spiral lines more densely arrange in specimens from Aleutian Islands (Figs. 16 A–B) than in those from Gulf of Alaska and Bering Sea (Figs. 15 B–E).

Digestive system with an oval buccal mass, surrounded by the central nervous system anteriorly (Fig. 17 A). Two salivary glands connect with the buccal bulb at the insertion point of the esophagus. Esophagus short, simple, thin-walled. Gizzard and gizzard plates absent. Radular formula 12 x 2.1.0.1.2. Innermost lateral teeth broad, with strong denticles, outer teeth hook-shaped (Figs. 15 G, 16C).

Male reproductive system with a short and simple prostate connected to an undifferentiated penis (Fig. 17 B).

Range. Aleutian Islands, Bearing Sea and Gulf of Alaska (Fig. 3 C). Depth range 0–148 m, typically shallower in the northernmost part of the range.

Etymology. Dedicated to the memory of Rae Baxter to honor his contributions to the taxonomy of the Alaskan marine fauna and for collecting the majority of the specimens of this species here examined.

Remarks. The North Atlantic species Philine indistincta Ohnheiser and Malaquias, 2013 is similar in radular morphology but the shells are more elongate and quadrangular (see Ohnheiser and Malaquias, 2013). It also has gizzard plates and the radular teeth denticles are much less prominent than in P. baxteri; finally the radular formula of P. indistincta is 1.1.0.1.1 instead of 2.1.0.1. 2 in P. b ax t er i.

Another superficially similar species is Laona quadrata (Wood, 1839), also from the North Atlantic, recently transferred to Laona by Oskars et al. (2015). It shares with Philine baxteri sp. nov. denticulate inner radular teeth, a similar male reproductive anatomy and punctuated lines on the shell. However, the shell morphology is different; Laona quadrata has a shorter and wider shell with a larger aperture narrowing abruptly posteriorly. The radular teeth of Philine baxteri sp. nov. also have more robust cusps with larger denticles.

Specimens from the Aleutian Islands have more compressed sculptural grooves and weaker denticles on the inner lateral teeth than those from the Gulf of Alaska; it is possible that Philine baxteri sp. nov. could constitute more than one species.