Leocrates iris Grube, 1878

Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), Zootaxa 4739 (1), pp. 1-114 : 59-63

Leocrates iris Grube, 1878 reinstated

Figs 32 , 33

Leocrates iris Grube, 1878: 105–106 ; Chamberlin 1919: 190; Treadwell 1926: 16.

Irma angustifrons: Hoagland 1920: 604 (non Grube, 1878).

Leocrates chinensis: Horst 1924: 193–194 (partim, non Kinberg, 1866); Pettibone 1970: 215 (non Kinberg, 1866; Pettibone listed the two USNM topotype lots below, but made no figures nor description).

Type material. Philippines and Samoa. Four syntypes ( MNHW 296 ), in two lots, each with two specimens, number 367 includes a small, dried-out specimen; the others damaged [body 15 mm long, 3 mm wide, 16 chaetigers. Prostomium as long as wide; lateral antennae without tips, as long as palps; palpophores 3 times longer than palpostyles; median antenna without tip, not reaching prostomial anterior margin. Eyes colorless, anterior eyes larger than posterior ones. Nuchal organs lobes horizontal C-shaped. Notochaetae from chaetiger 5; neurochaetae about 30 per bundle, blades long to short], and the other lot contains specimens 714 and 780 [in better condition, best one used for redescription below, the other slightly damaged. Body 14 mm long, 3 mm wide, 16 chaetigers. Eyes colorless, reniform, at least right anterior eye] .

Additional material. Philippines. One specimen ( ZMA V.Pol. 534.2), Sulu Islands, anchorage off North

Ubian, R/V Siboga Exped., Sta. 99 (06°07.5’ N, 120°26’ E), 16–23m, dredge and tow-net, lithothamnion bottom, 28-30 Jun. 1899 [12 mm long, 2 mm wide]. One specimen ( USNM 18966 ), USFS Albatross, Philippine Expedition 1907–1909, Sta. 5149, Sulu Archipelago, off Siasi, 4.5 km E off Sirun Island (05°33’00” N, 120°42’10” E) , 18 m, corals and shells, 18 Feb. 1908 [16 mm long, 3 mm wide]. Samoa. One specimen ( USNM 1548297 ), Pago Pago (14°16’46” S, 170°42’02” W) , May 1920, A.L. Treadwell, coll. [used for redescription]. Indonesia. One specimen ( ZMA V.Pol. 534.1), Lesser Sunda Islands, R/ V Siboga Exped., Sta. 53, Waingapoe ( Waingapu , 09°39’ S, 120°16’ E) , Sumba, Bay of Nangamessi , 36 m, trawl and shore exploration, coral sand, near the shore, mud , 21-22 Apr. 1899 [13 mm long, 2.5 mm wide]. One specimen ( ZMA V.Pol. 534.4), Sulawesi, R/ V Siboga Exped., Sta. 125, Siau Island (02°45’ N, 125°24’ E) , anchorage off Sawan, 27 m, dredge, townet, Monaco trap, reef-exploration, stones, 18-19 Jul. 1899 [8.5 mmm long, 1.5 mm wide]. One specimen ( ZMA V.Pol. 534.5), Maluku, R/ V Siboga Exped., Sta. 231 Ambon (03°42’ S, 128°10’ E) , at anchorage, 40 m, reef expl., coral, sand, 14-18 Nov. 1899 [19 mm long, 2.8 mm wide]. Three specimens ( ZMA V.Pol. 534.7), Lesser Sunda Islands, R/ V Siboga Exped., Sta. 315, Paternoster Island , anchorage E of Sailus Besar, 36 m, dredge, coral , 17-18 Feb. 1900 [7–11 mm long, 1–2 mm wide]. Vietnam. One specimen ( MNHN A71 ), southern region, Nam K ỳ or Cochinchine, 1906, Capt. St. Jacques & Capt. Modest (no further data) [15 mm long, 2 mm wide]. Marshall Islands. One specimen ( LACM 10885 ), Ralik Chain , Eniwetok Atoll , Lidilbut Island , corals, Sta. 1503 (no further data) , May 1952, H.S. Ladd, coll. [15 mm long, 3 mm wideMiddle]. Fiji. Two specimens ( USNM 19193 ), Suva (18°08’29.76” S, 178°26’30.84” E) , Apr. 1920, A.L. Treadwell, coll. (12–18 mm long, 1.5–2.0 mm wide]. French Polynesia. One specimen ( UF 3056 ), Society Islands, Moorea, Vaipahu (17°28’12.00” S, 149°49’48.00” W) , barrier reef, 0–2 m, algae and rocks, 24 Jan. 2012, M. Leray & L. Penland, coll. [14 mm long, 1.5 mm wide]. New Caledonia. One specimen ( MNHN Musorstom Lagon Est-726), Sta. 726 (21°20’06” S, 165°55’00” E) , 51 m, fine sand, Halimeda fragments, 12 Aug. 1986, B. Richer de Forges, coll. [13 mm long, 2.5 mm wide]. Australia. One specimen ( AM W4961 ), Warangol River mouth, Northeast coast (05°30’ S, 151°00’ E) , New Britain, 5 Sep. 1970, Turner et al., coll. [16 mm long, 3 mm wide]. One specimen ( AM 43841 ), Queensland, Lizard Island, Vicki’s Reef (14°41’17” S, 145°26’35” E) , 9 m, calcareous algae 13 Aug. 2013, M. Capa & J. Zanol, coll. [12 mm long, 2 mm wide].

Description (topotype details in brackets). Best syntype (MNHW 296, 714-780) complete, obconic, blunt anteriorly, tapered posteriorly ( Fig. 32A ); right parapodium of chaetiger 8 removed for observing parapodial features. Body colorless, 14 mm long, 3 mm wide; most cirri missing. [Best preserved topotype (USNM 1548297) complete ( Fig. 33A ), with a transverse dissection on the left side between chaetigers 3 and 4, and an oblique ventral dissection from mouth to chaetiger 10, one parapodium previously removed; left parapodium of chaetiger 9 dissected (kept in small container). Body colorless, 17 mm long, 2 mm wide. Many cirri on site].

Prostomium slightly longer than wide, slightly wider anteriorly ( Fig. 32B ). Lateral antennae with ceratophores distinct, without tips, slightly shorter than prostomium, as long as palps; palpophores 3 times longer than palpostyles (probably eroded). Median antenna short, tapered, not reaching anterior prostomial margin, inserted centrally. [Prostomium longer than wide, slightly wider anteriorly ( Fig. 33B ). Lateral antennae without tips, as long as palps, both directed ventrally; palpophores three times longer than palpostyles. Median antenna broken, scar inserted central to eyes ( Fig. 33C )].

Eyes colorless; other features unclear (Grube indicated anterior eyes reniform, one time larger, and slightly more separated than posterior ones). [Eyes dark brown; anterior eyes each 1 / 5 prostomial width, reniform or halfmoon shaped, twice larger than posterior ones, slightly more distant to each other than posterior round ones ( Fig. 33B, C ); in lateral view anterior and posterior eyes distinct].

Nuchal organs lobes as rectangular projections, posterior furrow narrow; lateral cilated bands not visible. Tentacular cirri missing (another syntype in same lot with cirri without tips, longest ones reaching chaetiger 5). [Nuchal organs lobes horizontal C-shaped lobes; lateral ciliated bands not visible. Tentacular cirri without tips, longest ones reaching chaetiger 5. Lateral cushions low, barely projected, entire, longitudinal striae visible].

Pharynx exposed. Anterior margin smooth, slightly eroded ( Fig. 32C ). Upper jaw larger and more anteriorly inserted than lower jaw. [Pharynx with about 20 marginal constrictions; upper jaw visible, lower one damaged after dissection ( Fig. 33D )].

Dorsal cirri missing (another syntype with cirri without tips, as long as body width including parapodia). Chaetigers 1–4 without notochaetae; notochaetae present along chaetigers 5–16, abundant, subdistally denticulate, denticles fine (notochaetae soft, surfaces eroded by long time in formalin solution). Notacicular lobes tapered, longer than dorsal cirrophores in middle segments; neuracicular lobes blunt ( Fig. 32D ); aciculae black. Neurochaetae about 30 per bundle, blades bidentate, guards decreasing in size ventrally, blades eroded, soft, fine details difficult to be observed, 3–12 times longer than wide ( Fig. 32E, F ). [Dorsal cirri with tips broken, as long as body width including parapodia. Chaetigers 1–4 without notochaetae. Notochaetae present along chaetigers 5–16, abundant, coarsely denticulate subdistally. Notacicular lobes tapered, blunt; neurochaetal lobes blunt ( Fig. 33E ); aciculae black. Neurochaetae about 30 per bundle, blades decreasing in size ventrally, 4–11 times longer than wide; blades bidentate, guard approaching subdistal tooth ( Fig. 33F )].

Posterior region tapered. Prepygidial segment with dorsal cirri 4–5 times longer than ventral ones. Pygidium with anus terminal, anal cirri missing. [Posterior region tapered. Preanal segment with dorsal and ventral cirri, cirrostyles broken medially, or completely. Pygidium tubular, anus terminal, anal cirri missing].

Oocytes not seen. [Gonad fragments seen by transparency in some parapodia; oocytes about 100 µm in diameter].

Variation. More recently collected specimens (USNM 19193) with palps and antennae of similar size, and palpophores twice larger than palpostyles (as indicated in the original description), slightly larger in larger specimen. Anterior eyes are less pigmented but about twice larger than posterior ones, and with a large anterolateral emargination, such that they are reniform, but their contourns are less well-defined. In both, notacicular lobes are tapered, neuracicular lobes conical, blunt, about as long as wide. It is interesting that these specimens were slightly darker than the one from Samoa (USNM 19194i). Provided they were collected and processed under similar conditions, this difference might be due to the fact that the Samoan specimen was longitudinally dissected, and the fixative might change the basic body wall pigmentation, and its gonads are unmature. No other difference was found. A single small specimen (UF 3056) from the French Polynesia had abundant dark brown spots along body; it is regarded as belonging to this species because this mottled pattern is unexpected, but there was no other diagnostic difference in comparison to other specimens herein regarded as conspecific.

Remarks. Leocrates iris Grube, 1878 has been regarded as a junior synonym of L. chinensis Kinberg, 1866 by Horst (1924) and by Pettibone (1970), and as a distinct species by Chamberlin (1919), and Treadwell (1926). Leocrates iris deserves to be reinstated because the main difference between these two species is the size of eyes, being large in L. iris (each 1 / 5 prostomial width), and small in L. chinensis (each 1 / 10 prostomial width).

On the other hand, L. iris resembles L. rizzoae n. sp. from the Seychelles, because they have notacicular lobes three times longer than wide, and about 30 neurochaetae per bundle in middle chaetigers. These two species differ in the shape of anterior eyes and in the size proportions between palpophores and palpostyles. In L. iris anterior eyes are reniform and palpophores are 2–3 times longer than palpostyles, whereas in L. rizzoae anterior eyes are emarginate, and palpophores are twice longer than palpostyles.

Hoagland (1920: 604) made no comments about the morphology of the species. Pettibone (1970) reexamined the specimen but made no comments or illustrations after it.

Distribution. Philippines, Samoa, Indonesia, Vietnam, Marshall Islands, Fiji, French Polynesia, New Caledonia, Australia, in coralline substrates from the intertidal to 51 m depth.

Figures

FIGURE 32. Leocrates iris Grube, 1878 reinstated, best syntype (MNHW 296, 714-780). A.Anterior region, dorsal view, SAS. B. Anterior end, dorsal view. C. Anterior region, ventral view. D. Chaetiger 8, right parapodium, anterior view, SAS (inset: notacicular lobe). E. Upper neurochaetal blades. F. Lowest neurochaetal blades. Scale bars: A: 1 mm, B: 0.4 mm, C: 0.8 mm, D: 0.3 mm, E: 90 μm, F: 70 μm.

FIGURE 33. Leocrates iris Grube, 1878 reinstated, non-type specimen (USNM 1548297). A. Dorsal view. B. Anterior region, dorsal view. C. Anterior end, dorsal view, MGS. D. Anterior end, ventral view after midventral dissection. E. Chaetiger 8, left parapodium, anterior view (inset: notacicular lobe). F. Same, lower portion of neurochaetal bundle. Scale bars: A: 1.4 mm, B: 0.9 mm, C: 0.4 mm, D: 0.6 mm, E: 0.3 mm, F: 120 µm.