Kristianides, Salazar-Silva, 2020

Salazar-Silva, Patricia, 2020, Paralbunea dayriti, Zoological Studies (Zool. Stud.) 59 (29), pp. 1-14 : 6-9

Subfamily Eulagiscinae Pettibone, 1997

Kristianides gen. nov. urn:lsid:zoobank.org:act:7A447D15-D3B3-4F8B-AA02-6CB6813A3EE3

Etymology: The new genus is named to honor the late Dr. Kristian Fauchald, in recognition of his valuable contributions to numerous studies on polychaetes, and especially for his unrestricted support for museums and research on scale worms, one of his favorite polychaete groups.

Gender: Masculine.

Type species: Kristianides cylindricum sp. nov.

Diagnosis: Eulagiscinae , body with many s e g m e n t s. Ve n t r a l l a m e l l a e t h i n, s e m i c i r c u l a r. Prostomium bilobed without cephalic peaks; no facial tubercle; two pair of circular eyes, small, dark; three antennae, median antenna with ceratophore short, inserted frontally with ceratostyle short, slender; lateral antennae with ceratophores indistinct, short, thick, inserted terminally as prostomial continuations, at the same level as median antenna; ceratostyle minute, slender. Palps slender, long. Tentacular segment not visible dorsally; tentaculophores with protruding thick acicula; segment two without nuchal fold. Fifteen pair of elytra on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, last six segments with dorsal cirri. Elytra thin, imbricate, covering dorsum; elytral margin with fringe of thin papillae and elytral surface with sclerotized microtubercles and macrotubercles. Parapodia birramous; notopodia and neuropodia well developed; notochaetae abundant, long, a few thicker and short, mostly slender with long spinous region and tips capillary; neurochaetae of two types, subacicular with rows of long spines, and long bare entire tips; supraacicular neurochaetae with longer spinous region and entire tips.

Remarks: Three subfamilies have been proposed in Polynoidae based on the terminal insertion of the lateral antennae as extensions of prostomium: Lepidonotinae Willey, 1902 , Lepidastheniinae Pettibone, 1989 , and Eulagiscinae Pettibone, 1997 . They have a similar prostomium but differ principally in the shape of parapodia. In Lepidonotinae neuropodia are entire without distinct pre-chaetal and post-chaetal lobes, and short notopodia. In Lepidastheniinae the neuropodia have distinct pre-chaetal and post-chaetal lobes, the acicula is not projected, and notopodia are reduced. Eulagiscinae was defined by having neuropodia and notopodia well developed; both with distinct pre-chaetal and post-chaetal lobes; acicula projected in a longer preacicular lobe and an occipital lobe.

Kristianides gen. nov. is characterized by having lateral antennae inserted terminally, as in Lepidonotinae and Lepidastheniinae , but in Kristianides gen. nov., both neuropodia and notopodia bear a projected pointed acicular lobe, corresponding with Eulagiscinae after Pettibone 1997. Therefore, this new genus is being referred to the latter subfamily. Kristianides gen. nov. differs from the other Eulagiscinae genera, Eulagisca McIntosh, 1885 and Pareulagisca, Pettibone, 1997 , because it lacks of an occipital fold and it has ventral lamellae. Recently Bonifácio and Menot (2019) emended the description of Eulagiscinae to include the absence of a nuchald fold, characters observed in the species of Bathymorea Pettibone, 1967. Thus Kristianides gen. nov. constitutes the fourth genus of Eulagiscinae and differs from the others of this subfamily as shown in key below.

Kristianides is also distinguished from other genera of others subfamilies provided with ventral lamellae as is indicated in table 1.

Kristianides cylindricum sp. nov. ( Figs. 4–7 ) urn:lsid:zoobank.org:act:FA6DF46D-A732-4B65-9705-62BE4C3E02C3

Material examined: Holotype USNM 075622 , Gulf of Mexico, off Alabama, Mississippi Sound, R / V Mississippi Sound , sta. 581, 30°11'35"N, 088°16'32"W, depth 12.2 m, 29 Oct. 1980, Army Corp of Engineers , coll.

Description: Holotype USNM 075622 complete. Body with 38 segments, length 1.5 cm, width 2.0 mm without chaetae, pale yellow pale, parapodia long, slender ( Fig. 4a ), venter markedly segmented ( Fig. 6b ).

Prostomium bilobed, wider than long, facial tubercle absent, without cephalic peaks ( Fig. 4b ). Eyes dark, small, on posterior prostomial half, anterior eyes dorsolateral; posterior eyes displaced anteriorly. Median antenna with thick ceratophore, inserted frontally, between prostomial lobes; slender ceratostyle papillated, shorter than prostomium length, tapered into filiform tip. Lateral antennae with stout, short ceratophores, inserted terminally as prolongations of prostomial lobes; ceratostyles thin, surface papillated, shorter than prostomial length. Palps long, thin, papillated, tapered into fine tips. Pharynx not everted.

Tentacular segment not visible dorsally; tentaculophores without chaetae; aciculae thick protruding. Tentacular cirri thin; long, almost palps length; surface papillated; tapering into filiform tips. Segment two without nuchal lobe ( Fig. 4b ).

Fifteen pairs of elytrophores on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32; first 12 pairs alternate with one dorsal cirri, except on segments 4 and 5; last six segments with dorsal cirri. Elytra translucent, imbricated, covering dorsum. Elytral margin with fringe of long, abundant papillae ( Fig. 5d ). Elytral surface with microtubercles and macrotubercles ( Fig. 5a–c, e ), and filiform papillae with globular tips ( Fig. 5e– f ). Microtubercles conical, amber in color ( Fig. 5f ); macrotubercles cylindrical-conical, amber in color ( Fig. 5e–g ).

Dorsal tubercles inconspicuous; elytrophores rounded. Dorsal cirri long, extended beyond neurochaetal tips ( Fig. 7a ), surface with short papillae; cirrophore cylindrical, long; ventral cirri short, papillated, tip filiform.

Parapodia biramous, separated from each other, almost as long as body width. Notopodia well developed, acicular lobe projected. Neuropodia long with distinct pre-chaetal and post-chaetal lobes; pre-chaetal lobe projected like an acicular lobe, post-chaetal lobe shorter ( Fig. 7a–b ).

Notochaetae more abundant than neurochaetae ( Fig. 7a–c ). First two notopodia with notochaetae thicker, short, curved, blunt tips, with a few capillary notochaetae; from third notopodia notochaetae longer; some shorter curved, lateral wit rows of inconspicuous spines, tips short ( Fig. 7d ); mostly longer spinous with capillary tips ( Fig. 7e ). Neurochaetae thicker than notochaetae; subacicular neurochaetae with rows of spines, tips entire, long, curved ( Fig. 7h–i ); supraacicular neurochaetae ( Fig. 7f ) longer, slender, spinous region long, spines long, tips capillary ( Fig. 7g ).

Pygidium with terminal anus; anal cirri lost. Ventral lamellae from segment 3, thin, depressed, wide, semicircular, with a bilobed appearance ( Fig. 6a–c ).

Type locality: Alabama, Mississippi Sound (30°11'35"N, 088°16'32"W).

Distribution: Only known from the type locality.

Etymology: The species is named after the shape of elytral macrotubercles, being cylindrical.

Remarks: Kristianides cylindricum n. sp. was previously identified as Phyllohartmania taylori Pettibone, 1961 because it has ventral lamellae, but in P. taylori the lateral antennae have ceratophores inserted ventrally, while in Kristianides they are inserted terminally, as prolongations of the prostomial lobes.

Lagisca lamellifera ( Marenzeller, 1879) was described with ventral lamellae, but its prostomium has cephalic peaks, and lateral antennae inserted ventrally on distinct ceratophores. Moore (1910) considered that the ventral lamellae referred to by von Marenzeller in L. lamellifera are not diagnostic, because they appear under certain conditions of preservation in many species. For Uschakov (1982), the ventral lamellae may only be present on large specimens of Gastrolepidia clavigera Schmarda, 1861 and might have a reproductive function, but Hanley (1989) found that their presence was not size-dependent. In Branchinotogluma Pettibone, 1985 the ventral lamellae and presence of long nephridial papillae are regarded as indicative of sexual dimorphism in males ( Zhang et al. 2018b); as indicated above, this dimorphism has been documented in polynoids, mainly from hydrothermal vents ( Glover et al. 2005).

The new species can be distinguished by the combination of their prostomium, ornamentation of its elytra, presence of a pair of ventral lamellae laterally on each segment, which are not frequent in the species of Polynoidae .

Figures

Fig. 4. Kristianides cylindricum sp. nov., holotype USNM 075622. a, Dorsal view of anterior region, showing some elytra still attached (el); b, prostomium showing segment two without projections. Scale bars: a = 1.33 mm; b = 0.70 μm.

Fig. 5. Kristianides cylindricum sp. nov., holotype USNM 075622. a, b, elytra of middle segments, showing fringe and tubercles; c, close-up of elytral surface, showing macrotubercles; d, elytral margin, showing fringe of papillae; e, g, macrotubercles sclerotized cylindrical; f, microtubercles sclerotized, and papillae with globular tips. Scale bars: a = 830 μm; b = 463.71 μm; c = 511.72 μm; d, e = 125 μm; f = 37 μm; g = 38 μm.

Fig. 6. Kristianides cylindricum sp. nov., holotype USNM 075622. a, Anterior region, ventral view, showing lamellae, b, c, median segments, ventral view, showing lamellae. Scale bars: a = 0.984 mm; b = 0.647 mm; c = 0.492 mm.

Fig. 7. Kristianides cylindricum sp. nov., holotype USNM 075622. a, Parapodium left showing dorsal cirri; b, parapodium left without cirrophore and abundant notochaetae; c, parapodium showing notochaetae and neurochaetae; d, thick notochaetal tips; e, spinulose region of slender bpnotochaetae; f, supraacicular neurochaetal tips; g, spines of supraacicular neurochaetae; h, neurochaetae, complete; i, neurochaetal tips; j, neurochaetal base showing rows of spines. Scale bars: a, b = 510 μm; c = 520 μm; d, e, g, i, j = 50 μm; f, h = 100 μm.