Laeonereis longula, Conde-Vela, 2021

Conde-Vela, Víctor M., 2021, Revision of Laeonereis Hartman, 1945 (Annelida: Phyllodocida: Gymnonereidinae), with a review of shaft morphology in nereidids, Journal of Natural History 55 (7 - 8), pp. 381-455 : 414-419

Laeonereis longula sp. nov.

( Figures 5 (f,i), 6, 15(a–f), and 16(a–o))

Laeonereis culveri Hartman 1951: 44–45 , pl. 13, figs 3–4. Pettibone 1971: 15–16, fig. 6a–l (partim, non Webster, 1879).

Type material

Northwestern Atlantic Ocean, United States. Holotype USNM 33294 and paratypes USNM 1490792 (3), Sapelo Island , Georgia, marsh near ‘ Chocolate’, high tide, 16 March 1961, Coll. M. Gray.

Additional material

USNM 33294 (6), Sapelo Island, Georgia, marsh near ‘Chocolate’,high tide, 16 March 1961, Coll. M. Gray. USNM 1490793 (7), Cedar Key, Florida, 13 December 1959, Coll. Polychaete Class. USNM 1490794 (3), trinity-by-the-cove, Naples, Florida, Coll. C. Long, 28 December 1958.

Type locality

Sapelo Island, Georgia, United States.

Etymology

Named after the Latin word longulus, -a, -um, meaning ‘large in extent’, referring to the large notopodial dorsal ligules present in this species.

Description

Holotype ( USNM 33294 ) complete, in good condition, some parapodia previously removed, 48 mm long, 2 mm wide at chaetiger 10, 132 chaetigers ( Figure 15 (a,c)) . Paratypes ( USNM 1490792 ) two anterior fragments, one posterior fragment and two middle fragments, and a complete specimen, in regeneration, 25 mm long, 1 mm wide at chaetiger 10, 82 chaetigers . Specimens homogeneously brownish, glandular masses sometimes visible, blue pigmented, more conspicuous towards posterior end ( Figure 15 (d)).

Prostomium hexagonal, longer than wide, anterior margin deeply cleft, dorsal groove deep, reaching anterior pair of eyes ( Figure 15 (a,e)); antennae cirriform, as long as dorsal groove ( Figure 15 (a,e)); eyes black, subequal, anterior eyes reniform, posterior ones rounded ( Figure 15 (a,e)). Achaetous ring 1.0–1.5 times longer than first chaetiger ( Figure 15 (a,e)); four pairs of anterior cirri, cirrophores conspicuous, longest pair of cirri reaching chaetigers 3–4 ( Figure 15 (a,e).

Pharynx everted. Jaws brownish, 15 teeth, some ensheathed, cutting edge completely dentate ( Figure 5 (i)). Maxillary ring: I = 1–1 tuft of verticillate rod-like papillae; II = 1–1 tuft of verticillate rod-like papillae; III = 3 tufts of verticillate rod-like papillae; IV = 1–1 tuft of verticillate rod-like papillae ( Figure 5 (f)). Oral ring: V = 0; VI = 1–1 triangular papilla; VII– VIII = one ridge row with 5 rounded papillae, 1 papilla on each A–C region ( Figure 5 (f)).

Pattern of pedal glands ( Figure 6 ). UpG elliptical and smaller than MeG in anterior chaetigers, turning into a row of small glands in middle chaetigers. LoG absent in both anterior and middle chaetigers. MeG triangular or elliptical and 3 times larger than PoG in anterior chaetigers, becoming rounded and subequal to PoG in middle chaetigers. PoG becoming shorter than middle chaetigers.

First two chaetigers with neuroaciculae only, remaining ones with both noto- and neuroaciculae. In first two chaetigers ( Figure 16 (a)), dorsal cirri linguiform. Dorsal ligules subconical, blunt, as long as wide, 2.5–3 times longer than dorsal cirri, 1.5 times longer than neuroacicular ligules. Neuroacicular ligules digitiform, 1.3 times wider than long; postchaetal lobes digitiform, 1.2 times longer than wide, subequal to dorsal ligules, twice as long as neuroacicular ligules, 1.2 times longer than neuropodial ventral ligules; neuropodial ventral ligules digitiform, twice as wide as long, 1.8 times longer than ventral cirri. Ventral cirri subconical.

In anterior chaetigers ( Figure 16 (b,c)), dorsal cirri linguiform. Notopodial dorsal ligules subconical, blunt, 1.5 times wider than long, 3 times longer than dorsal cirri, 1.7 times longer than prechaetal lobes; notopodial dorsal ligules quickly becoming digitiform, 1.3 times longer than wide, 6 times longer than dorsal ligules, 2.3 times longer than prechaetal lobes; prechaetal lobes digitiform, 1.5–2.0 times wider than long, disappearing towards middle chaetigers; notopodial ventral ligules subconical, blunt, twice as long as prechaetal lobes, as long as neuroacicular ligules. Neuroacicular ligules subconical, blunt, as long as wide, 1.7 times longer than neuropodial ventral ligules; postchaetal lobes digitiform, as long as wide, as long as neuroacicular ligules; neuropodial ventral ligules digitiform, 3 times wider than long, 2.3 times longer than ventral cirri, both neuropodial ventral ligules and ventral cirri becoming shorter towards middle chaetigers. Ventral cirri subconical.

In middle chaetigers ( Figure 16 (d,e)), dorsal cirri linguiform. Notopodial dorsal ligules ensiform, 3–4 times longer than wide, 9 times longer than dorsal cirri, 2.5–3.0 times longer than notopodial ventral ligules, becoming shorter towards posterior chaetigers; prechaetal lobes absent; notopodial ventral ligules subconical, 1.3 times longer than wide, as long as neuroacicular ligules. Neuroacicular ligules subconical, 1.3 times wider than long, 2.5 times longer than neuropodial ventral ligules; postchaetal lobes absent; neuropodial ventral ligules digitiform, 3.3–3.5 times wider than long, 8 times longer than ventral cirri. Ventral cirri subconical.

In posterior chaetigers ( Figure 16 (f,g)), dorsal cirri linguiform. Notopodial dorsal ligules ensiform, 1.7 times longer than wide, 5–7 times longer than dorsal cirri, twice as long as notopodial ventral ligules and becoming as long as towards posteriormost chaetigers; prechaetal lobes absent; notopodial ventral ligules subconical, 1.5–1.8 times longer than wide, 1.5 times longer than neuroacicular ligules. Neuroacicular ligules subconical, 1.2 times longer than wide, 4 times longer than neuropodial ventral ligules; postchaetal lobes absent; neuropodial ventral ligules digitiform, 4.5 times wider than long, 6.5 times longer than ventral cirrus. Ventral cirri subconical.

In posteriormost chaetigers ( Figure 16 (h,i)), dorsal cirri linguiform. Notopodial dorsal ligules ensiform to digitiform, 1.5–2.0 times wider than long, twice as long as dorsal cirri and becoming shorter than and disappearing towards posterior end; notopodial ventral ligules digitiform, 2.0–6.0 times longer than wide, 1.0–1.2 times longer than neuroacicular ligulse. Neuroacicular ligules subconical, 1.2 times longer than wide, 1.3–2.0 times longer than neuropodial ventral ligules; postchaetal lobes absent; neuropodial ventral ligules digitiform, 2.5–3.5 times wider than long, 3–8 times longer than ventral cirri. Ventral cirri subconical to digitiform.

Notochaetae homogomph spinigers. Neurochaetae homogomph spinigers in supraacicular fascicles, homogomph spinigers and falcigers in sub-acicular fascicles; subacicular homogomph falcigers absent in anterior chaetigers.

Notopodial and neuropodial homogomph spinigers pectinate, minute teeth, teeth decreasing in size towards tip ( Figure 16 (j–l)). Neuropodial sub-acicular falcigers pectinate, teeth minute, distal tooth stout, falcate; blades 14–15 times longer than wide in middle chaetigers, becoming 30 times longer than wide in posterior chaetigers ( Figure 16 (m–o)).

Pygidium funnel-shaped ( Figure 15 (c,d)); anal cirri cirriform, 4–5 times longer than width of pygidium ( Figure 15 (c,d)).

Remarks

Pettibone (1971) included the material herein examined from Sapelo Island, Georgia, under L. culveri , without further explanation and despite presenting a plate depicting considerable variability in notopodial dorsal ligules ( Pettibone 1971, fig. 7(a–h)). Pettibone (1971, p. 16) summarised the differences in her figures 6(i–l) and 7(e–h) with the phrase ‘Parapodia of middle and posterior segments smaller, with fewer lobes...’. This explains why differences among the species were overlooked and the material was included with L. culveri . Here this decision is rejected, in agreement with other authors ( Orensanz and Estivariz 1971; Orensanz and Gianuca 1974; Dean 2001; de Jesús-Flores et al. 2016; de León-González et al. 2017).

The main differences between L. longula sp. nov. and L. culveri are focused on the notopodia of middle and posterior chaetigers. In L. longula the medial chaetigers have notopodial dorsal ligules ensiform, 3–4 times longer than wide, 9 times longer than dorsal cirri, and 2.5–3.0 times longer than notopodial ventral ligules; whereas in L. culveri they are subconical, 1.2 times longer than wide, 7–8 times longer than dorsal cirri, and 1.2 times longer than notopodial ventral ligules. In posterior chaetigers of L. longula sp. nov., the notopodial dorsal ligules are ensiform, 1.7 times longer than wide, and 5–7 times longer than dorsal cirri; whereas in L. culveri they are subconical, 1.5–1.7 times wider than long, and 5 times longer than dorsal cirri. Some differences can be noted in the neuropodia: in L. longula sp. nov., the neuroacicular ligules are 1.3 times wider than long in middle chaetigers and 1.2 times longer than wide in posterior ones, whereas in L. culveri they are 2.5 times wider than long in middle chaetigers and 1.3 times wider than long in posterior ones. Also, the pattern of pedal glands is different between them: in L. longula sp. nov., LoG is absent throughout body and UpG consists in a row of small glands along the notopodial dorsal ligules of middle parapodia, whereas in L. culveri LoG is present in anterior chaetigers and UpG consists in a sole, large gland in middle parapodia.

Laeonereis longula sp. nov. is very similar to L. orensanzi comb. nov. because of the long, ensiform notopodial dorsal ligules, being the only two species in the genus to have this feature. There are, however, some important differences between them: in L. longula sp. nov. jaws have uncovered teeth, whereas in L. orensanzi comb. nov. they are ensheathed; in middle chaetigers of L. longula sp. nov., notopodial dorsal ligules are 9 times longer than dorsal cirri and 2.5–3.0 times longer than notopodial ventral ligules, whereas in L. orensanzi comb. nov. they are 4 times longer than dorsal cirri and 2.2 times longer than notopodial ventral ligules; in L. longula sp. nov., the neuropodial ventral ligules are always conspicuous along the body, whereas in L. orensanzi comb. nov. they become progressively shorter until they disappear in the posterior chaetigers; in L. longula sp. nov., the blades of the neuropodial homogomph falcigers are 14–15 times longer than wide in anterior chaetigers and up to 30 times longer than wide in posterior chaetigers, whereas in L. orensanzi comb. nov. they are 9–10 times longer than wide in anterior chaetigers and slightly longer in posterior chaetigers.

Figures

Figure 5. Foregut, papillae and jaws in Laeonereis species. (a) non-type specimen of L. acuta (ECOSUR- P3102), ventral dissection; (b) non-type specimen of L. pandoensis (ECOSUR-P3103), dorsal dissection; (c) and (d) rounded papillae in area VIII from paratype of L. orensanzi comb. nov. (UANL 7840); (e) rodlike, verticillate papillae from syntype of L. culveri from area IV (USNM 541); (f) everted pharynx from paratype of L. longula sp. nov. (USNM 1490792), labels indicate papillae on the pharyngeal areas; (g) left jaw of the paratype of L. brunnea (USNM 43404), dorsal view; (h) left jaw of the syntype of L. culveri (USNM 541), dorsal view; (i) left jaw of the paratype of L. longula sp.nov. (USNM 1490792), dorsal view; (j) left jaw of L. orensanzi comb. nov. (UANL 7840), dorsal view; (k) left jaw of non-type of L. pandoensis (ECOSUR-P3103), dorsal view. Dark areas in (a) and (b) are due to remnants of Shirlastain staining; (f) is stained with methyl green. Scale bars: a, b = 0.5 mm; c–e, j = 25 µm; f–i, k = 0.1 mm. Abbreviations:Es, oesophagus; Jw, jaw; Pa, papilla; Ph, pharynx; Pp, palpophore; Ps, palpostyle.

Figure 6. Arrangement of pedal glands in Laeonereis species. Abbreviations: DoG = dorsal gland; LoG = lower distal pedal gland; MeG = medial pedal gland; PrG = proximal pedal gland; UpG = upper distal pedal gland.

Figure 15. Laeonereis longula sp. nov. (a, e, c), holotype (USNM 33294); (b, f), non-type (USNM 1490793); (d), paratype (USNM 1490792). (a) anterior end, dorsal view; (b) anterior end, dorsal view; (c) posterior end, dorsal view; (d) posterior end, dorsal view; (e) close-up of prostomium, dorsal view; (f) pharynx everted, ventral view. Scale bars: a–b = 1 mm; c–f = 0.5 mm.

Figure 16. Laeonereis longula sp. nov. (a–o), holotype (USNM 33294). (a) chaetiger 2, left parapodium; (b) chaetiger 10, left parapodium; (c) chaetiger 21, left parapodium; (d) chaetiger 42, left parapodium; (e) chaetiger 60, left parapodium; (f) chaetiger 82, left parapodium; (g) chaetiger 102,left parapodium; (h) chaetiger 120, left parapodium; (i) chaetiger 129, left parapodium; (j) notopodial homogomph spiniger, chaetiger 10; (k) notopodial homogomph spiniger, chaetiger 21; (l) supra-acicular homogomph spiniger, chaetiger 60; (m) sub-acicular homogomph falciger, chaetiger 21; (n) sub-acicular homogomph falciger, chaetiger 42; (o) sub-acicular homogomph falciger, chaetiger 82. Scale bars: a– h = 0.2 mm; i = 50 µm; j–o = 10 µm.