Loimia Malmgren, 1866

Nogueira, João Miguel Matos, Hutchings, Pat & Carrerette, Orlemir, 2015, Terebellidae (Annelida, Terebelliformia) from Lizard Island, Great Barrier Reef, Australia, Zootaxa 4019 (1), pp. 484-576 : 545-548

Genus Loimia Malmgren, 1866

Loimia . — Hutchings & Glasby 1988: 26; Carrerette & Nogueira 2015: 3–7.

Type-species. Terebella medusa Savigny, 1818 , by monotypy.

Diagnosis. Transverse prostomium attached to dorsal surface of upper lip; basal part sometimes with eyespots; distal part shelf-like. Buccal tentacles usually about same length as region with notopodia, or slightly longer. Peristomium forming lips; hood-like upper lip; small, swollen lower lip, restricted to oral area. Segment 1 reduced dorsally, with pair of large lobes directed anteriorly and covering upper lip, mid-ventrally fused to each other and indented anteriorly, partially exposing lower lip; lobes of segment 1 originating at variable position from dorsal to ventral sides of body. Segment 2 usually only conspicuous dorsally, laterally covered by lobes of segment 3 and fused to segment 3 mid-ventrally, forming anterior part of single, protruding mid-ventral shield between segments 2–3 or 2–4. Segment 3 with pair of large lateral lobes, of variable size and shape; segment 4 rarely with pair of shorter lobes. Paired dorso-lateral arborescent branchiae present on segments 2–4, 3 pairs. Anterior segments with glandular, rectangular to trapezoidal, smooth to slightly corrugated mid-ventral shields; mid-ventral groove extending posteriorly from termination of mid-ventral shields. Short, rectangular to conical notopodia beginning from segment 4, extending for 17 segments, until segment 20. Narrowly-winged notochaetae in both rows throughout. Neuropodia present from segment 5, as low ridges until termination of notopodia, as elongate pinnules thereafter. Neurochaetae throughout as pectinate short-handled avicular uncini, arranged in partially intercalated to completely separate double rows, in back to back arrangement, from segment 11 until termination of notopodia, on segment 20; uncini with short base, dorsal button closer to base of main fang, frequently inconspicuous, and crest with single vertical series of progressively shorter secondary teeth, main fang not always clearly marked. Nephridial papillae on segment 3, genital papillae on segments 6–8, posterior to notopodia and dorsal; short papillae, not always conspicuous. Pygidium smooth to papillate (Carrerette & Nogueira 2015).

Remarks. Loimia is a well known genus of Terebellidae . Live specimens are frequently large and brightly coloured. This genus is easily recognized by the presence of pectinate uncini, a feature unique among terebellids. However, the distinction between the species of Loimia is much more difficult, especially because most descriptions do not provide details of the morphology of the lobes and other important characters (Carrerette & Nogueira 2015).

Live specimens of members of Loimia have a remarkable character, which is the presence of a bright, blood red region at the termination of mid-ventral shields ( Figs 2 J–L; 3A–B, D–F). Similar blood red ventral regions are also observed among members of at least some species of Lanice ( Fig. 3 G), Lanicides ( Fig. 2 C) and Pista . Although this region seems to be a blood sinus, we could not confirm this after examining live material and apparently the bright red colour is due only to pigmentation, as there is no particular concentration of blood in this area. After preservation, some pigmentation may remain, as a dark mid-ventral spot extending for several segments, or completely fade. Although it is not visible in live material due to the blood red colour, this region still has mid-ventral shields, but those are deeply grooved transversely, instead of smooth to slightly crenulate, as anterior shields.

Four species of Loimia are known from Australian waters, L. batilla Hutchings & Glasby, 1988 , L. ingens Grube, 1878 , L. ochracea Grube, 1878 , and L. triloba Hutchings & Glasby, 1988 . Of those, L. batilla was described from material collected in QLD, and L. ingens and L. triloba have been previously found in the GBR, although these species have not been found at Lizard Island ( Hutchings & Glasby 1988). In the present study, we found four species of Loimia , all new to science, described below.

Figures

FIGURE 2. Live specimens. A – B. Pista kristiani n. sp. AM W. 45451, MI QLD 2445; C – D. Lanicides rubra n. sp. AM W. 44272, MI QLD 2344; E – G. Eupolymnia chlorobranchiata n. sp. AM W. 45455, MI QLD 2446; H – I. Pistella franciscana n. sp. H. Discarded specimen; I. AM W. 44593, MI QLD 2394; J – L. Loimia tuberculata n. sp; J – K. Spec. AM W. 44280, MI QLD 2359; L. Discarded specimen. Photos: A – K—Alexander Semenov, L—Gary Cranitch.

FIGURE 3. Live specimens. A – C. Loimia pseudotriloba n. sp. AM W. 47810, MI QLD 2336; D – F. Loimia juani n. sp.; D. AM W. 44261, MI QLD 2335; E. AM W. 44518, MI QLD 2381; F. AM W. 44263, MI QLD 2336; G – I. Lanice viridis n. sp. AM W. 44611, MI QLD 2400. Photos: A – I—Alexander Semenov.