Loimia minuta Treadwell, 1929

Londoño-Mesa, Mario H. & Carrera-Parra, Luis F., 2005, Terebellidae (Polychaeta) from the Mexican Caribbean with description of four new species, Zootaxa 1057, pp. 1-44 : 21-22

Loimia minuta Treadwell, 1929

Figures 5 H–N

Loimia minuta Treadwell, 1929: 10 –11; Figures 28–30.

Material examined: Mexican Caribbean: ECOSUR TERE­11 E2 (1) Leeward of Contoy Island (21°30’8.4’’N 86°47’45.3’’W), Oct. 1983, by trawling. (1) Majahual (18°40’09.6’’N 87°43’01.4’’W), 22 Mar. 2000. (1) Paraíso, Cozumel Island (20°56’38’’N 86°59’35’’W), 5 Jun. 1995. (1) Leeward of Contoy Island (21°30’8.4’’N 86°47’45.3’’W), 3 Mar. 2001, 2 m.

Description: Specimen complete, mature female, with pale body on preserved material, with 105 segments, 62 mm long; thorax 13 mm long and 3 mm wide ( Figures 5 H–I). Thorax well defined, as wide as anterior abdominal region. Abdomen paler than thorax, posterior body white, tapering to pygidium; coelom of abdominal segments with small eggs. Tentacles small and smooth. Tentacular membrane well developed. Eyespots absent. Upper lip with reduced spoon­like free edge; lower lip reduced, hidden by the first lateral lappet. Two pairs of lateral lappets on segments 1 and 3; first pair surrounding ventrally and laterally the tentacular membrane; second pair of lappet emerging laterally on segment 3 as a thin membrane, as long as first neuropodium, and as high as twice the anterior notopodia, not extending across the ventral side. Three pairs of branchiae, branched, starting from segment 2; first pair longer than the second, and the last the shorter; nevertheless, differences in size are not visible. Nephridial papillae indistinct. Ten ventral shields, starting from segment 2; divided in two (bisected) by transverse lines on midthorax, in three (trisected) on posterior shields. Ventral surface smooth, without midventral groove. Parapodia from segment 4, extending for 17 segments. Notochaetae of two types, long chaetae, thick, bilimbate capillaries ( Figure 5 J), 6–7 per fascicule; and short chaetae smooth and thin capillaries ( Figure 5 K), 7–8 per fascicle. Neuropodia from segment 5, uncini arranged in single row until segment 10, in double rows on segments 11–20, in back to back position, and in single rows from segment 21 until the pygidium; with uncini pectinate, thoracic uncini with five teeth ( Figure 5 L), and the abdominal uncini with 6 teeth. Thoracic and abdominal uncini similar in shape and size, with short and narrow subrostrum, without subrostral process, with short anterior process directed downwards, basis strongly curved, with high and short posterior process, as a heel; posterior filament absent; long and curve occipitium, terminating in a capitium with 4–5 teeth. Pygidium with 6 long and digitate anal papillae ( Figure 5 O).

Remarks: The total number of segments in all specimens complete revised varies from 102 to 105 segments. This species was synonymized with Loimia medusa by Fauvel (1914) and Hartman (1956) because of the belief of the wide and cosmopolitan distribution in warm seas of the latter species. However, after the revision of type material, L. minuta differs from L. medusa by having notochaetae of two sizes, although they are both bilimbate, and by having ventral shields annulated (divided by two or three transversal lines) after the seventh shield. Specimens from the Mexican Caribbean belong to L. minuta .

Distribution: Florida and Mexican Caribbean.

Figures

FIGURE 5. Loimia salazari sp. nov. Lateral view; B. Ventral view; C. Chaetae from segment 5; D. Uncinus from segment 5; E. Uncinus from segment 14; F. Uncinus from segment 104; G. Pygidium with anal papillae. Loimia minuta: H. Lateral view; I. Ventral view; J. Chaetae bilimbate from segment 10; K. Chaetae capillary from segment 10; L. Uncinus from segment 10; M. Uncinus from segment 25; N. Pygidium with digitate anal papillae. Scale bars: A, B 5 mm; C, J, K 0.05 mm; D, E, F, L; M 0.02; G, H, I 1 mm; N 0.5 mm.