Loimia megaoculata Carrerette & Nogueira, 2015, sp. nov.
Creators: name: Carrerette, Orlemir
name: Nogueira, João Miguel De Matos
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Terebellida
Terebellidae
Loimia
Loimia megaoculata

description: Loimia megaoculata sp. nov.
(Figures 3–6; Table 1)
Type series. Holotype MZUSP 0 2363 (coll. 22º12'33"S 40º13'25"W, 99 m, 05.Jul.2009). Paratype 1 MZUSP 0 2364 (coll. 22º46'49"S 41º3'39"W, 78 m, 02.Jul.2009). Paratype 2 MZUSP 0 2365 (coll. 21º58'59"S 40º25'16"W, 52 m, 25.Feb.2009). Paratype 3 AM W.47671 (coll. 22º12'26"S 40º14'13"W, 92 m, 24.Feb.2009). Paratype 4 AM W.47672 (coll. 22º3'37"S 40º24'15"W, 55 m, 06.Jul.2007). Paratype 5 USNM 1273436 (coll. 22º1'18"S 40º20'19"W, 60 m, 24.Jul.2009). Paratype 6 USNM 1273437 (coll. 22º19'27"S 40º37'25"W, 73 m, 24.Jul.2009). Paratype 7 ZUEC 16674 (coll. 22º51'57"S 40º57'35"W, 92 m, 03.Jul.2009). Paraype 8 ZUEC 16675 and paratype 9 ZUEC 16676 (coll. 22º19'27"S 40º37'25"W, 73 m, 04.Jul.2009). Paratype 10 MZUSP 0 2366 (coll. 22º17'37"S 40º27'5"W, 103 m, 04.Jul.2009).
Additional material examined. Project HABITATS/PETROBRAS: State of Rio de Janeiro—Campos Basin: 21º42'33"S 40º9'5"W, 147 m, 25.Aug.2009, 4 specs; 22º7'35"S 39º54'21"W, 680 m, 30.Aug.2009, 4 specs; 22º19'27"S 40º37'25"W, 73 m, 04.Jul.2009, 3 specs; 22º17'37"S 40º27'5"W, 103 m, 04.Jul.2009, 1 spec.
Additional material examined for comparison. Loimia grubei sensu Blankensteyn (1988) — ZUEC 6131 (coll. 24°53'00"S 46°46'07"W, 47 m, 1 spec.); ZUEC 6043 (coll. 24°16'00"S 46°01'02"W, 50 m, 1 spec.). L. medusa sensu Blankensteyn (1988) — ZUEC 6044 (coll. 26°29'05"S 48°21'04"W, 38 m, 1 spec.). Loimia bandera Hutchings, 1990: holotype, AM W.201924 (coll. 6 km S.E off Port Island, New Territories, 24 m, S/edge, coll. 5.Apr.1986); paratypes AM W.201926–7 (coll. Hong Kong, Tap Mun, 22°29'N 114°22'E, Apr.1986). Loimia batilla Hutchings & Glasby, 1988: holotype, AM W.5162 (coll. Moreton Bay 20°26'S 147°05'E, Queensland, Australia, coll. 1971); paratype AM W.7097 (coll. Middle Banks off Tangalooma, 27°12'S 153°21'E, Queensland, Australia, coll. 1972); paratype AM W.7106 (coll. Middle Banks off Tangalooma, 27°12'S 153°21'E, Queensland, Australia, coll. 1972); paratype AM W.7107 (coll. Moreton Bay 20°26'S 147°05'E, Queensland, Australia, coll. 1970). Loimia triloba Hutchings & Glasby, 1988: paratype AM W. 200558 (coll. Australia, Queensland, Low Isles, Great Barrier Reef, 16°23'S 145°34'E). Loimia medusa (Savigny in Lamark, 1818): neotype, LACM-AHF Poly 1656 (coll. Upper Persian Gulf, coll. Tetra Tech, Apr.1982, shallow shelf).
Description. Small, fragile, cylindrical worms, not markedly swollen anteriorly (Figs 3 C–E; 5A, C), anterior segments compact, all about same length except for shorter segments 1 and 2; chaetigers progressively longer on segments 12–20. Complete specimens with 26–48 (26) segments, 3.7–5.1 (4.1) mm long, 0.3–0.9 (0.3) mm wide (Table 1). Preserved body colourless, except for dark brown transverse ventral band at intersegmental line of segments 2 and 3. Prostomium at base of dorsal side of upper lip; basal part of prostomium with 2 rows of eyespots, upper row with 5–6 large eyespots at each side, progressively smaller laterally, arranged in oblique band (Fig. 3 A, C, G); other row at posterior margin of basal part of prostomium, with much smaller, irregularly scattered eyespots, in broad band; distal part of prostomium forming shelf-like process from which short and cilindrical buccal tentacles originate (Figs 3 A–G; 5A–F). Peristomium restricted to lips; upper lip short, wider than long, nearly circular and folded laterally; lower lip short, rectangular, cushion-like, partially hidden by membrane connecting lobes of segment 1 (Figs 3 A–G; 5A–I). Segment 1 visible entirely, dorsally short, with relatively short paired lobes originating dorso-laterally, aligned with line of notopodia; lobes with oblique dorsal margins, continuing across ventrum as low lobes; distally rounded, roughly circular, barely reaching mid-length of upper lip, then oblique towards lower lip; tips and ventral edges connected by membrane (Figs 3 A–G; 5A–B, E–F). Segment 2 short, conspicuous laterally and dorsally, ventrally separated from segment 3 forming first mid-ventral shield (Figs 3 A–F; 5B, F); segment 3 longer than the previous ones, with paired low lobes, thin, ear-like, distally rounded; with wide bases about as large as tips of lobes, originating dorso-laterally, near anterior margin of first pair of notopodia (these on segment 4), terminating aligned with ventral edge of neuropodia, laterally to partially fused mid-ventral shield of segments 3–4 (Figs 3 A–G; 5A–B, E–I); dorsal margins oblique, terminating far from bases of branchiae (Figs 3 A–G; 5A–B, E–I); segment 4 partially fused mid-ventrally to the mid-ventral shield of segment 3; following anterior segments about same size. Three pairs of branching branchiae, on segments 2–4, each with short basal stem (Fig. 5 C–F); pairs of branchiae progressively shorter, all ventrally aligned. Rectangular, smooth, swollen midventral shields on segments 2–12, slightly crenulated and completely separated from each other, smooth from segment 5, progressively narrower to last (Figs 3 A–B, D–F; 5A–B); a distinctly narrower pad on segment 13 is frequently present, divided by two transverse bands; from segment 14, shields replaced by mid-ventral groove extending posteriorly (Figs 3 A–B; 5A–B). Cylindrical, short notopodia, on segments 4–20, bearing narrowlywinged chaetae in both rows, those from posterior row longer, with wings on distal half of chaetae (Figs 4 A–D; 6A–C). Neuropodia beginning from segment 5, as low rectangular ridges slightly raised from surface of body until segment on which notopodia terminate (Figs 3 A–B, D–F; 5A–B, E–F), thereafter as elongate, prominent pinnules (Fig. 3 A, H); neuropodia bearing pectinate uncini, arranged in double rows on segments 11–20, tori aligned ventrolaterally from segment 5 to posterior body, rows partially intercalated on ventral edges of neuropodia, then completely separate, uncini in crest-to-crest to back-to-back arrangement (Figs 4 D; 6F–G). Uncini pectinate, higher than long, with concave base, prominent, triangular heel directed backwards, and prow downwardly directed, continuing as long ligament (Figs 4 E–H; 6E–I); uncini of region with notopodia with six teeth, progressively shorter upwards, basal-most tooth larger, in line with prow, distal-most tooth as short spine on top, barely visible under light microscope, conspicuous under SEM (Figs 4 D–F; 6E–H); neuropodia from region after notopodia terminate with uncini with up to 6–7 teeth, frequently varying within tori, sometimes distal-most tooth sided by one minute tooth at each lateral (Figs 4 G; 6I). Nephridial and genital papillae not visible. Anus surrounded by crown of short, rounded papillae (Fig. 3 H).
Remarks. Loimia megaoculata sp. nov., is shorter than most species of Loimia and has large eyespots, to our knowledge not found in any other species of the genus. Loima megaoculata sp. nov., has eyespots arranged in two rows, the upper one with 5–6 large eyespots on each side, beginning dorso-laterally and progressively smaller lateral and upwards, with other row at posterior margin of basal part of prostomium, with small, irregularly scattered eyespots.
Two other species of Loimia have eyespots on basal part of prostomium, L. triloba Hutchings & Glasby, 1988 (Table 2), originally described from Australia (Hutchings & Glasby 1988, 1995; Londonõ-Mesa & Carrera-Parra 2005; Londonõ-Mesa 2009) and L. medusa (Hutchings & Glasby 1995; JMMN personal observation). In addition to the eyespots, L. triloba also has uncini with 5–6 teeth (Fig. 2 D, F, K, L), similar to L. megaoculata sp. nov. However, L. triloba differs from L. megaoculata sp. nov., in having two rows of small eyespots, arranged laterally, lacking larger eyespots as in L. megaoculata sp. nov. In addition, L. triloba has lobes of the segment 1 continuing dorsally as free, completely encircling the body, lateral lobes of segment 3 with the base narrower than the tip, and a pair of shorter lateral lobes on segment 4 (Fig. 1 B, G). In contrast, in L. megaoculata sp. nov., the lobes of the segment 1 originate dorso-laterally, at line of notopodia, with large mid-dorsal gap, the lobes of segment 3 have bases at least as wide as tips, and there are no lobes on segment 4.
The neotype of L. medusa also has eyespots, but few, only laterally (Hutchings & Glasby 1995; JMMN, personal observation). Loimia medusa differs from L. megaoculata sp. nov., however, in addition to the arrangement and shape of the eyespots, by having a pair of large, high and circular lobes on segment 1; nearly circular ones on segment 3, with narrower base than tip, upper dorsal margins reaching the bases of the branchiae; rectangular and progressively longer mid-ventral shields, as well as uncini with 4–5 teeth only (Figs 1 D, J; 2C, G, L). In contrast, L. megaoculata sp. nov., also has distally rounded, roughly circular lobes of segment 1, but they are distinctly shorter than those of L. medusa, the lobes of segment 3 have bases at least as wide as tips, the mid-ventral shields are also rectangular, but they are evenly-sized, instead of progressively longer, and the uncini have 6–7 teeth.
Four other species resemble L. megaoculata sp. nov., with regard to the presence of ventral shields extending to segment 12, L. bandera, L. batilla, L. medusa and L. bermudensis Verrill, 1900, although in L. megaoculata sp. nov., a distinctly narrower pad on segment 13 is also frequently present. A comparison of all these species is provided in Table 2, together with the other species used for comparisons with the remaining species described in this paper.
TABLE 2. List of species of Loimia used for comparison with the species described in this paper, with the main morphological characters used for the identification. Sources: Hutching and Glasby (1988); Hutchings (1990); characters of Loimia bandera, L. batilla, L. medusa, and L. triloba examined directly from type-material.
Type locality Eyespots Lateral lobes, segment 1 Lateral lobes, segment 3 Ventral Nephridial and Uncini (number of
shields (segs) genital papillae teeth)
(segs) bandera Pacific Ocean, Hong Absent Originating dorso-laterally, Originating laterally to 3– 12, 6–8 5–6
Kong close to origin of branchiae of origin of branchiae, rectangular
segment 2, continuing across almost fused to anterior
ventrum as low lobes; lobes margin of segment 3
distally straight
batilla Queensland, Australia Absent Mid-dorsally fused to each Nearly circular, oblique, 3–12 3, 6–8 5–6
other, forming low collar originating laterally to the across dorsum; oblique dorsal origin of branchiae,
margins, relatively short and extending across ventrum distally rounded
bermudensis Bermuda, Atlantic Ocean Absent Large, projecting forwards, Wide base, nearly same 3–12 – 5
well-developed, extending length as lobes of
laterally surrounding upper segment 1, terminating
lip and ventrally lower lip away from mid-ventral
shield, and with dorsal
edge almost as long as
first lobe, slightly
developed, not covering
base of branchiae
crassifilis SE Asia, Philippines Absent Foliaceous lobes, with rounded 5–11 – 4–5 end, connecting each other
by a membrane. Well expanded
grubei Philippine Islands Absent High, with rounded end Low, rounded end 3–14 – 5–6
......continued on the next page TABLE 2. (Continued)
Type locality Eyespots Lateral lobes, segment 1 Lateral lobes, segment 3 Ventral Nephridial and Uncini (number (morphology) (morphology) shields genital papillae of teeth: (Aterior (segments) (segments) X Posterior)
ingens SE Asia, Philippines Absent Mid-dorsally fused to each Well developed, with pair – – 3–7
other, forming low collar arising from junction of
across dorsum segments 2–3
medusa Red Sea Present Large and distally rounded, Large, nearly circular, with 3–12 3, 6–8 4–5
dorso-laterally, aligned with narrower base, dorsal margin
notopodia of segment 4, reaching bases of branchiae
with oblique dorsal margin
minuta Dry Tortugas, Florida Absent Projecting forwards, With short base, not connected 2–17 – 5
laterally surrounding upper to ventral shield, and with
lip dorsal edge slightly developed
salazari Xcacel, Mexican Absent Covering both upper and Well developed dorsal lobe 2–14, 17 – 4–5 Caribbean lower lips; laterally, covering base of branchiae
reaching level of notopodia
triloba Three Isles, Queensland: Dark, arranged Mid-dorsally fused to each Nearly circular originating at 3–16 6–8 5–6 Great Barrier Reef, in 2 lateral rows other, forming low collar level of dorsal edge of
across dorsum; oblique neuropodia, terminating far
dorsal margins and distally from ventral edges of
rounded neuropodia
Loimia bandera was originally described from Hong Kong (Hutchings 1990) and differs from L. megaoculata sp. nov., in having a narrow basal V-shaped part of the prostomium lacking eyespots, and uncinial teeth exhibiting minor differences in size from the basal- to the distalmost teeth (Fig. 2 A, E), while in L. megaoculata sp. nov., the basal part of the prostomium is longer, not V-shaped and has eyespots, and the uncinial teeth are markedly shorter distally. In addition, the mid-dorsal gap between the lobes of the segment 1 of L. bandera is distinctly narrower than present in L. megaoculata sp. nov. (Fig. 1 F), while the lobes of the segment 3 are larger and oblique, instead of rounded. The Australian species L. batilla also differs from L. megaoculata sp. nov., in the same characters as L. bandera, i.e., prostomium lacking eyespots, and uncinial teeth exhibiting minor differences in size from the basalto the distalmost teeth (see Table 2).
Loimia bermudensis Verrill, 1900, which was described from Bermuda and has never been collected again since the original description (Londoño-Mesa 2009), differs from L. megaoculata sp. nov., in the number of uncinial teeth, 5 teeth per uncinus throughout the body, instead 6 on anterior body chaetigers and 7 on posterior ones, as in L. megaoculata sp. nov.. In addition, L. bermudensis has all uncinial teeth of similar size, while in L. megaoculata sp. nov., considerable differences occur (Figs 4 D–G; 6E–I).
Finally, L. megaoculata sp. nov., shares some characteristics with L. armata sp. nov., also described in the present paper, as discussed in the Remarks of the description of that species (see below).
Etymology. We attribute to this taxon the epithet “ megaoculata ” in reference to the presence of the large eyespots on the basal part of prostomium.
Type locality and distribution: State of Rio de Janeiro (Campos Basin).
description: Published as part of Carrerette, Orlemir & Nogueira, João Miguel De Matos, 2015, The genus Loimia Malmgren, 1866 (Annelida: Terebellidae) off the Brazilian coast, with description of three new species and notes on some morphological characters of the genus, pp. 1-31 in Zootaxa 3999 (1) on pages 8-16, DOI: 10.11646/zootaxa.3999.1.1, http://zenodo.org/record/289185