Hesione hartmanae, Salazar-Vallejo, 2018

Salazar-Vallejo, Sergio I., 2018, Revision of Hesione Savigny in Lamarck, 1818 (Annelida, Errantia, Hesionidae), Zoosystema 40 (12), pp. 227-325 : 259-261

Hesione hartmanae n. sp.

( Figs 18 , 19 )

urn:lsid:zoobank.org:act:F50811AA-A413-4219-AAF1-0B3DD68E2E4F

Hesione splendida – Monro 1933: 26 (non Savigny in Lamarck, 1818).

Hesione intertexta – Hartman 1940: 212, pl. 33, figs 30-31 (partim, fig. 30).

TYPE MATERIAL. — Eastern Pacific. Galápagos Islands. Holotype, LACM 10158 , RV Velero III, Sta. 310 (00°18’20”N, 90°31’00”W), off Bindloe Island, 27 m depth, rock, tangles, 3.XII.1934. Paratypes, LACM 10159 , RV Velero III, Sta. 167 (01°14’37”S, 90°28’08”W), Post Office Bay , Charles Island , 27 m depth, rocks, 19.I.1934 [four complete paratypes 21-40 mm long, 4-5 mm wide; some more or less macerated, most cirri and neurochaetal blades on site; chaetal lobes variably invaginated; right parapodium of chaetiger 9 in 3 specimens removed (kept in vial); even the smallest one has oocytes, each about 100 µm] .

ADDITIONAL MATERIAL. — Eastern Pacific. Galápagos Islands. 1 specimen, BMNH 1932.12 .24.129, RV St-George Pacific Expedition, 1923-1924, Galápagos Sta. 9, C. Crossland coll. [35 mm long, 5 mm wide; almost colorless, a few poorly defined transverse bands along some anterior chaetigers; antennae twice as long as wide; anterior eyes slightly larger than posterior ones; right parapodium of chaetiger 12 previously removed; right parapodium of chaetiger 10 removed for observation (kept in vial); acicular lobe double, tines digitate, blunt, upper tine slightly longer than lower one; neurochaetal blades broken or without blades; blades bidentate, subdistal tooth smaller, guards most broken, if complete surpassing subdistal tooth] . — 2 specimens, LACM 10160 ), RV Velero III, Sta. 169 (00°46’18”S, 90°19’27”W), Academy Bay, Indefatigable Island , 28-45 m depth, sand, rock, algae, 20.I.1934 [28-31 mm long, 3-4 mm wide; one macerated, the other in better condition; most cirri and neurochaetal blades on site; chaetal lobes variably invaginated; right parapodium of chaetiger 9 from both specimens removed (kept in vial); upper acicular lobe twice as long as lower one; largest specimen with oocytes, each about 100 µm].

ETYMOLOGY. — This species is named after Dr Olga Hartman, eminent taxonomist of polychaetes from the Allan Hancock Foundation, University of Southern California, to honor her immense legacy including lots of publications and new taxa, and because she provided some relevant details to recognise these specimens as a different, undescribed species. The name is a noun in genitive ( ICZN 1999: art. 31.1.2).

DISTRIBUTION. — Galápagos Islands, Ecuador, in subtidal to 45 m depth, in mixed substrates.

DIAGNOSIS. — Hesione with prostomium rectangular; parapodia with dorsal cirri basally cylindrical, dorsal cirrophore twice as long as wide; larger acicula blackish; acicular lobe double, tines long, digitate, subequal; neurochaetal blades bidentate, 3-6 times as long as wide; subdistal tooth smaller; guards approaching distal tooth.

DESCRIPTION

Holotype, LACM 10158, mature, complete, subcylindrical, tapered posteriorly, posterior region bent laterally, first four chaetigers with ill-defined brownish transverse bands, progressively paler ( Fig. 18A ) in ethanol; some cirri lost, others in regeneration, most neurochaetal blades on site; right parapodium of chaetiger 8 removed (kept in vial). Body 41 mm long, 5 mm wide.

Prostomium slightly as long as wide, anterior margin truncate with a deep depression, lateral margins straight, slightly divergent posteriorly, posterior margin deeply cleft about ¼ prostomial length (reaching level of posterior eyes), longitudinal depression indistinct ( Fig. 18B ). Antennae minute, digitate, twice as long as wide, about as long as free interocular distance. Eyes brownish, circular; anterior eyes slightly larger and more distant to each other than posterior ones.

Tentacular cirri undulated, longest reaching chaetiger 4. Lateral cushions projected, with 2 sections in anterior to median chaetigers, and with 3 ones in posterior segments.

Parapodia with chaetal lobes tapered, truncate, dorsal cirri with cirrophores 3 times as long as wide ( Fig. 18C ); cirrostyle cylindrical, smooth basally, then annulated, become articulated in distal half, as long as half body width (without parapodia). Ventral cirri smooth, tapered, surpassing chaetal lobe.

Neuraciculae blackish, 1-2 markedly thicker and 1 very thin, very close to each other, making their detection difficult. Acicular lobe double, tapered, blunt, upper lobe twice as long as lower one, half as long as chaetal fascicle width ( Fig. 18C [inset]).

Neurochaetae about 30 per bundle, blades bidentate (sometimes guard and teeth eroded), subdistal tooth smaller, blades at a certain angle from the handle, 3-6 times as long as wide, decreasing in size ventrally, guard approaching distal tooth ( Fig. 18D [insets]).

Posterior region tapered into a blunt cone ( Fig. 18E ); pygidium swollen, slightly depressed, anus with 6 digitate papillae.

Pharynx not everted in holotype (smaller paratype with pharynx almost fully everted, margin slightly eroded, made up by three rings, basal one slightly corrugated, dorsal papillae rounded, as long as wide). Oocytes about 100 µm in diameter.

Variation

A rather weak dorsal darkening in one of the smaller paratypes, even less defined in largest paratype. Prostomial shape varies depending on pharynx exposure from having a squarrish outlook, with lateral margins slightly divergent in smallest paratype ( Fig. 19A, B ), to one with rounded lateral margins, markedly divergent if the pharynx is not exposed ( Fig. 19D, E ). In smaller paratypes, acicular lobes with upper tine twice as long as lower ones ( Fig. 19C ), or of similar size in largest paratype ( Fig. 19F ).

REMARKS

Hesione hartmanae n. sp. was likely recorded before under three different names. Monro (1933: 26) cited what Cyril Crossland noticed about the pigmentation of some Panamian Hesione : “There are five transverse brown bands of irregular outline anteriorly, the first on the anterior border of the peristomium, the others occupying the anterior third of each segment, the middle third being white, while the posterior third is a light brown but darker than the general body color behind the fifth segment.” Monro referred that specimen to H. splendida Savigny in Lamarck, 1818 , which had been observed alive and described with a pearly iridescent body, but without pigmentation. It must be noted that this Panamian specimen had been less than 10 years in ethanol before Monro studied it, and he indicated there was no pigmentation left on its body.

Hartman (1940: 212) preferred to use H. intertexta Grube, 1878 , and, as indicated below in the remarks for H. panamena Chamberlin, 1919 , her illustrations show an acicular lobe double with tines of similar size, which are not present in H. intertexta , meaning she had two species in her material. It seems she was unaware of the previous indications by Horst (1924: 193), who emphasised that acicular lobes were of very different size and shape in H. intertexta : a longer, digitate and the other one shorter, rounded. Different sized tines are also present in H. panamena , as indicated above. Hartman made no indication of transverse bands but stated that in her material: “most individuals retain the reticulated, fulvous pattern on the dorsum of the anterior segments, but in some there are almost none.” This fading is typical for those species having longitudinal thin lines along the body. In some of the specimens regarded as belonging to H. hartmanae n. sp., there is a fine indication for darker tranverse areas in anterior segments, despite the fact they have been in ethanol for about 70 years.

As indicated in the key below, H. hartmanae n. sp. resembles H. picta Müller, 1858 and H. reticulata von Marenzeller, 1879 . Their main difference is the length of the acicular lobe in comparison to the width of the corresponding chaetal lobe. In H. hartmanae n. sp. it is longer, about half as long as chaetal fascicle width, whereas it is shorter (1/3 as long) in the two other species.

Figures

FIG. 18. — Hesione hartmanae n. sp., holotype, LACM 10158: A, anterior region, dorsal view; B, prostomium, dorsal view (arrows point to antennae); C, chaetiger 8, right parapodium, anterior view (inset: acicular lobe); D, same, neurochaetal blades (insets: tips of blades); E, posterior region, dorsal view. Scale bars: A, 2.2 mm; B, 0.3 mm; C, 0.6 mm; D, 65 µm; E, 1.5 mm.

FIG. 19. — Hesione hartmanae n. sp., paratypes, LACM 10159: A, smallest paratype, anterior region, dorsal view; B, same, prostomium and everted pharynx (arrow points to dorsal papilla); C, same, chaetiger 9, right parapodium, anterior view (inset: acicular lobe); D, largest paratype, anterior region, slightly oblique dorsal view; E, same,prostomium slightly oblique dorsal view; F, same, chaetiger 9, right parapodium, anterior view (inset: acicular lobe). Scale bars: A, 1.3 mm; B, 0.7 mm; C, 0.4 mm; D, 1.8 mm; E, 0.3 mm; F, 0.6 mm.