Chloeia gilchristi McIntosh, 1924

Salazar-Vallejo, Sergio I., 2023, Revision of Chloeia Savigny in Lamarck, 1818 (Annelida, Amphinomidae), Zootaxa 5238 (1), pp. 1-134 : 63-65

Chloeia gilchristi McIntosh, 1924 reinstated

Fig. 28

Chloeia gilchristi McIntosh, 1924: 5 ; McIntosh 1925: 15–16, Pl. 1, Figs 7 , 8 ; Day 1934: 27–29, Fig. 4 ; Hartman 1959: 131. Chloeia inermis: Day 1960: 295 ; Day 1967: 123–124, Fig. 3.1.l–q (non de Quatrefages, 1866).

Type material. Indian Ocean, South Africa. Neotype ( BMNH 1934.1.19.41), Durban, sandy mud, without depth or date, Mr. Bevin, coll.

Diagnosis. Chloeia with bipinnate branchiae from chaetiger 4, progressively smaller posteriorly; middorsal bands regular, not constricted posteriorly; caruncle pale; harpoon notochaetae without basal tine; neurochaetae acicular and spurred.

Description. Neotype (BMNH 1934.1.19.41), bent ventrally, severely damaged, anterior end previously cut off, several parapodia or chaetal fascicles removed, many branchiae torn off, most chaetae broken, most cirrostyles lost ( Fig. 28A ); body fusiform, 54(6+48) mm long, 12 mm wide, 35(5+30) chaetigers.

Neotype brownish, chaetae transparent, soft; dorsal and ventral cirri pale; branchiae pale. Venter pale, midventral band barely paler than surrounding areas.

Prostomium anteriorly entire. Eyes blackish, anterior eyes slightly larger than posterior ones. Median antenna inserted at anterior caruncular margin, tip broken, 2/3 as long as caruncle ( Fig. 28B ), slightly longer than right lateral antenna (left one lost). Lateral antennae bases separate from each other, palps broken, size relationship to antennae unknown. Mouth ventral on chaetiger 3. Pharynx partially exposed; lips darker, basal ring smooth, exposing three longitudinal (vertical) lobes.

Caruncle pale, bent laterally, trilobed, tapered, posterior region broken, reaching chaetiger 3. Median ridge plicate, with about 11 vertical folds remaining, almost completely concealing lateral lobes. Lateral lobes narrow, with about 12 vertical folds.

Bipinnate branchiae from chaetiger 4, continued throughout body, parallel along body, many broken ( Fig. 28C ); progressively larger posteriorly (many lost), largest by chaetiger 24–25, progressively smaller thereafter. Chaetigers 24–25 with 8–9 lateral branches.

Parapodia biramous, notopodia with cirriform branchiae along chaetigers 1–3 (only one left in left notopodium of chaetiger 3), about 1/3 as long as dorsal cirri. Dorsal cirri (few remaining) slightly longer than bipinnate branchiae along median chaetigers, size relationship unknown in posterior chaetigers (dorsal cirri lost). Second ventral cirri (left) with cirrophores 2× longer and wider, and cirrostyle 2× longer than adjacent ones, directed dorsally. Median ventral cirri directed ventrolaterally, as long as one subsequent segment.

Chaetae most broken. Complete chaetae with distal fragile hoods, often eroded. Notochaetae in anterior chaetigers aciculars, some spurred with tiny spur ( Fig. 28D ), major tines 10–20× longer than spurs. Median chaetigers with two types of notochaetae: aciculars with tips tapered, mostly broken or partially dissolved ( Fig. 28F ), and harpoon-chaetae (illustrated by Day 1934, not seen). Neurochaetae all aciculars of three different widths, all with tips mucronate; a few with minute spurs, barely visible in some anterior chaetigers ( Fig. 28E ), major tines about 10–20× longer than spurs, indistinct in median chaetigers ( Fig. 28G ).

Posterior region tapered; pygidium with anus terminal; anal cirri pale, subcylindrical, blunt, 4× longer than wide ( Fig. 28H ).

Live pigmentation. Unknown; Day (1934) indicated dorsum was homogeneously grayish brown, without dorsal spots.

Remarks. Chloeia gilchristi McIntosh, 1924 was briefly described with a 50 mm long specimen collected in mud at 270 m depth, off Durban; because there is no dorsal pigmentation pattern, and by having bipinnate branchiae from chaetiger 4, becoming progressively smaller posteriorly, it belongs in the group tumida. In addition, after its fusiform body, acicular or spurred neurochaetae, and branchiae with lateral branches tapered, it resembles C. Baird, 1868 from India, redescribed below. These two species differ, however, in three features: body color, complexity of the caruncle, and neurochaetae; C. gilchristi has a brownish body, its caruncular median ridge has 11 vertical folds, and there are spurred neurochaetae along anterior segments, and acicular onwa in median segments, whereas in C. tumida the body is pale, the caruncular median ridge has about 38 vertical folds, and all neurochaetae are spurred.

After McIntosh (1924: 5), the holotype had brownish chaetae having “the tips simple pointed,”, as opposed to being furcates, with neurochaetae having “no trace of serrations or of a spur was present in any.” A more complete description and illustrations were added in a subsequent publication, including some details for smaller specimens. The body was described as dull brownish with yellow to golden chaetae, dorsal cirri were dark brown along their distal half ( McIntosh 1924: 5; 1925: 15–16), and a harpoon-chaetae and a neurochaetae were illustrated. However, there was no indication for the start of branchiae. He compared C. gilchristi with C. inermis de Quatrefages, 1866 and C. tumida Baird, 1868 , the former with few or no harpoon chaetae, the latter with small spurs in neurochaetae, and concluded that “the fact that here (in C. gilchristi ) few serrated, and no bifid bristles occur, differentiates this ( C. gilchristi ) from the ordinary … Chloeia .” However, the comparison was incomplete because no further differences were indicated from C. tumida . Baird (1868: 232) noted that C. tumida was white and illustrated its (harpoon) notochaetae as subdistally swollen, whereas other notochaetae were tapered. On the contrary, C. gilchristi was brownish and its notochaetae are blunt, not tapered; further, the subdistal swell in harpoon notochaetae is an artifact. Consequently, the two species are herein regarded as different after the pigmentation of their body wall, the complexity of the caruncular median ridge, and the type of neurochaetae.

Day (1934: 28), after the study of the herein proposed neotype, clarified several features. He indicated the dorsum is grayish without marks; median antennae ¾ as long as caruncle; eyes of similar size; branchiae from chaetiger 4, each with 5–6(10) lateral branches; notochaetae smooth and finely denticulate; neurochaetae spurred; anal cirri cylindrical, about 4× longer than wide. However, he hesitated about using chaetal features for clarifying its specific status because “it is impossible to say how much the form of the bristles has been modified by the strong formalin in which the specimens had been preserved.” After regarding it likely identical with C. euglochis Ehlers, 1887 , described from Florida, he concluded “until the bristles and coloration of a well-preserved specimen have been examined it is as well to keep them separate.”

Day (1960: 295, 1967: 120) listed C. gilchristi McIntosh, 1925 as a junior synonym of C. inermis de Quatrefages, 1866 (see below), described from New Zealand, and referred that “the setae agree perfectly with Monro’s description.” The latter had indicated ( Monro 1936: 80) “the chaetae show no trace of serrations.” This synonymy must be rejected because Day (1960: 295) noted that there was a middorsal purple line, and that branchiae start in chaetiger 4. However, there is no colored line in C. inermis , but a pale one is visible in fresh specimens, but most important, their bipinnate branchiae start in chaetiger 5. Further, Day (1967: 123) noted that the local specimens have no dorsal color markings but living or recently collected specimens of C. inermis have a pale longitudinal middorsal band throughout the body, over a pinkish background.

After all this information it is obvious C. gilchristi is different from C. inermis , and the taxonomic status of the former must be defined by proposing a neotype and fulfilling the qualifying conditions ( ICZN 1999, Art. 75.3) as follows:

The current synonymy, after Day (1960, 1967), must be rejected and the taxonomic status of C. gilchristi must be defined by proposing a neotype because the species delineation has been confused, although the species name is valid and deserves to be reinstated, and this procedure is an exceptional need for improving the taxonomy in the group ( ICZN 1999, Art. 75.3.1).

Consequently, the neotype has been diagnosed, described and illustrated for clarifying the differences with similar taxa, and for ensuring the recognition of the specimen designated ( ICZN 1999, Art. 75.3.2–3).

The material including the type specimens were sent to Dr. McIntosh during the early 1920s. However, the specimens were not returned to any South African museum, because the type material for C. gilchristi is missing in the corresponding catalogue ( SAMA 1958), it is not in the Iziko Museums of South Africa (J. Kara 2021, in litt.), and they were not deposited in the Natural History Museum, where most of McIntosh type material is deposited (E. Sherlock 2021, in litt.). Consequently, the type material is regarded as lost or destroyed ( ICZN 1999, Art. 75.3.4).

The neotype was collected in the same South African region, and it was compared to the original description by Day (1934), who used another specimen, herein proposed as neotype, and found some additional features for completing the original description, but the neotype matches the original specimens in having most chaetae unidentate, as opposed to being furcate, and it is herein regarded as conspecific ( ICZN 1999, Art. 75.3.5–6).

The neotype has been deposited in the Natural History Museum, London, and it has a long-standing tradition in curating and making their collections available for study ( ICZN 1999, Art. 75.3.7).

After some West African specimens recorded as C. euglochis Ehlers, 1887 , or especially as C. viridis Schmarda, 1861 , some authors have regarded C. venusta de Quatrefages, 1866 as a junior synonym. This idea was proven wrong by Guy (1964: 178) and he emphasized the differences in chaetae; his comments on C. viridis match C. gilchristi instead, especially after the neurochaetal furcates with tiny spurs.

Distribution. Off South Africa, in subtidal sediments.

Figures

FIGURE 3. Chloeia mezianei sp. n., non-type specimen (NHMD 915074). A. Left lateral view. B. Anterior end and pharynx, seen from above. C. Same, right lateral view. Scale bars: A, 1 mm; B, 0.6 mm, C, 0.5 mm.

FIGURE 4. Chloeia fusca M’Intosh, 1885, non-type specimen (UF 4368). A. Ventral view. B. Ventral view after body wall removed. C. Same, after Methyl Green staining. D. Same, lower half of digestive tube removed. (AI, anterior intestine; MB, midventral band (nerve chord); MR, muscular ridge; Oe, oesophagus; PI, posterior intestine; R, rectum; St, stomach). All scale bars: 1 mm.

FIGURE 7. Chloeia amoureuxi sp. n., holotype (MMSUCO Amp 2). A. Oblique dorsal view. B. Anterior end, left lateral view. C. Median segments, dorsal view. D. Chaetiger 3, notochaetal tips. E. Same, neurochaetal tips. F. Chaetiger 16, harpoon notochaetae. G. Same, neurochaetal tips. H. Posterior region, dorsal view. Scale bars: A, 0.7 mm; B, 0.05 mm; C, 1.5 mm; D, 160 μm; E, 110 μm; F, 180 μm; G, 30 μm; H, 2 mm.

FIGURE 8. Chloeia amoureuxi sp. n., epitoke (MNHN 860.1). A. Anterior region, dorsal view. B. Anterior end, dorsal view. C. Anterior end, right lateral view. D. Posterior region. Scale bars: A, 1.8 mm; B, 0.5 mm; C, 0.6 mm; D, 1.5 mm.

FIGURE 28. Chloeia gilchristi McIntosh, 1924, reinstated, neotype (BMNH 1934.1.19.41). A. Anterior fragment in frontal view, rest of body in dorsal view. B. Anterior fragment, dorsal view. C. Median chaetigers, dorsal view. D. Chaetiger 3, notochaetae (inset: notochaetal tip). E. Chaetiger 3, neurochaetae. F. Chaetiger 18, notochaetal broken tips. G. Chaetiger 16, neurochaetal tips. H. Posterior region, dorsal view. Scale bars: A, 13 mm; B, 1 mm; C, 1.6 mm; D, F, 90mμm; E, 30μm; G, 50 μm; H, 1.9 mm.