Lovenella gracilis Clarke, 1882

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141: 36-40

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https://doi.org/10.11646/zootaxa.4689.1.1

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lsid:zoobank.org:pub:41BFBBDF-41AD-4329-B6B9-CF38D64815A6

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scientific name

Lovenella gracilis Clarke, 1882
status

 

Lovenella gracilis Clarke, 1882 

Figs. 9View FIGURE 9 a–g

Lovenella gracilis Clarke, 1882: 139  , pl. 9, figs. 25–39.— Shier, 1965: 42 (in part).

not Lovenella gracilis  .— Joyce, 1961: 61, pl. 14, figs. 2, 3.— Shier, 1965: 42 (in part), pl. 23 [= Lovenella grandis Nutting, 1901  ].

Type locality. USA: Chesapeake Bay , 3–10 ftm (5–18 m) ( Clarke 1882: 135)  .

Material examined. Sanibel Island, beach at Lighthouse Point, on detached Thalassia  in water along shore, 13 December 2017, one colony, 4 mm high, with gonothecae, coll. D. Calder, ROMIZ B4351.— Fort Myers Beach , on dead sand dollars ( Mellita quinquiesperforata  ) near low water, 19 January 2018, several colony fragments, up to 5 mm high, without gonothecae, coll. D. Calder, ROMIZ B4352  .— Sanibel Island , beach at Lighthouse Point, 26°26’55”N, 82°01’08”W, on detached Syringodium  in water along shore, 21° C, 34.5‰, 19 March 2018, one colony, 3 mm high, without gonothecae, coll. D. Calder, ROMIZ B4353GoogleMaps  .

Non-Florida material examined. USA: Virginia, York River entrance off Ellen Island , 37°15’N, 76°25’W, 06 August 1966, several colonies, with gonophores, coll. D. Calder, ROMIZ B1548GoogleMaps  .— USA: South Carolina, Folly Beach , 18 November 1973, intertidal, on Mulinia lateralis  and adhering barnacles, coll. D. Calder, ROMIZ B1551  .— USA: New Jersey, Avalon , 01 September 2001, on Donax  , coll. J. Dougherty, ROMIZ B3504  .— USA: South Carolina, Bulls Bay , 32°55.9’N, 79°36.2’W, 5 m, 06 January 1976, coll. D. Calder, ROMIZ B1546GoogleMaps  ( Lovenella  sp.).

Remarks. Clarke (1882) described both hydroid and young medusa stages of this species from the Chesapeake Bay region, USA. While assigning the binomen Lovenella gracilis  to it, he expressed uncertainty about its relationships and systematic position. Such questions still need attention. Given its resemblance to L. clausa ( Lovén, 1836)  from northwest Europe, including habit of growth, turbinate hydrothecae, proboscis morphology, and number of tentacles and opercular facets, Clarke decided to refer his new species to Lovenella Hincks, 1868  [1869] rather than create a new genus for it. While recognizing certain similarities between it and L. clausa  , he regarded the two as distinct. Clarke’s illustrations show that his hydroids differ in having: (1) a hydrocaulus that is segmented beyond the base by single nodes into a series of cylindrical internodes rather than being annulated or wrinkled; (2) hydrothecae that are relatively shallow and funnel-shaped rather than deep and nearly cylindrical; (3) an operculum that is not distinctly demarcated from the hydrotheca. From accounts of the medusa stage of L. clausa  by Hincks (1871) and Russell (1936a, as Eucheilota hartlaubi  ; 1936b, as E. clausa  ; 1953, as L. clausa  ), several differences are also immediately apparent between the planktonic stages of the two species: (1) gonads are developed at liberation in L. gracilis  , but they do not appear until several days after release in L. clausa  ; (2) interradial marginal cirri occur in L. clausa  but not in L. gracilis  ; (3) the umbrella is oval in cross-section in L. gracilis  but circular in L. clausa  . The two species are clearly different.

In his original description of L. gracilis, Clarke (1882)  did not specify in detail where his specimens were collected. Although his work was done in Chesapeake Bay, Clarke spent research time there at both Crisfield, Maryland, and Fort Wool, Virginia. The type locality is therefore listed here simply as Chesapeake Bay.

Fraser (1912a, b) erroneously reported the European L. clausa  from the east coast of the United States, and included L. gracilis  as its synonym. In examining specimens from Bogue Sound, North Carolina, parts of his description and two of his figures ( Fraser 1912b, fig. 26B, 26C) were taken from accounts of L. clausa  by Hincks (1868 [1869], 1871) and Hartlaub (1897). He later recognized that the two species were distinct ( Fraser 1944: 174), acknowledged that his report of L. clausa  from eastern North America was wrong, and stated that the European species had not been observed in the western Atlantic. Regrettably, descriptions and illustrations actually based on those Carolinian hydroids by Fraser (1912b: 364, fig. 26A, 1944: 174, pl. 31, fig. 147b) conform more closely with characters of L. grandis Nutting, 1901  rather than L. gracilis  . Hydrothecae of his specimens were much deeper than those of L. gracilis  , and his drawings show distinct crease lines separating the opercular facets from the hydrothecal margin. Fraser’s record of the species from North Carolina is therefore assigned to L. grandis  here. Specimens referred by Fraser (1912b) to L. clausa  from Woods Hole, Massachusetts, were not illustrated and are of uncertain identity. Errors in characterization of L. gracilis  in Fraser’s publications lead to confusion about the species in subsequent works on hydroids of this coast. For example, Defenbaugh & Hopkins (1973) considered specimens much like and probably conspecific with L. gracilis  from Texas to be a new species, while a clearly different one resembling L. grandis  was misassigned to it. Specimens referred to L. gracilis  from Seahorse Key, Florida, by Joyce (1961), and part of those from the Cape San Blas area, Florida, by Shier (1965), also appear to have been misidentified. From descriptions of the operculum by Shier (“There are eight opercular sections; the basal hinge of these sections is often indistinct”), however, both species may have been present in her collections. Ones with “indistinct hinges” were likely assigned correctly to L. gracilis  . Identifications of the hydroid of L. gracilis  should be based on the original description of Clarke (1882), or on later accounts of specimens from the same general locality ( Calder 1971, this work), rather than on information in the guidebook of Fraser (1944). To further document the distinguishing characters of L. gracilis  , topotypic specimens from southern Chesapeake Bay region (ROMIZ B1548) were examined during this study and are illustrated here ( Figs. 9e, fView FIGURE 9).

Huvé (1952) compared the medusa stages of L. gracilis  and Dipleuron parvum Brooks, 1882  from Beaufort, North Carolina, and concluded that they were identical. He thereupon applied the binomen Dipleuron gracilis  to the species. His opinion that they were conspecific was shared by me ( Calder 1971), although I retained the name L. gracilis  for it. The specific name gracilis  of Clarke (1882), published in January of that year, has priority over parvum  of Brooks (1882), published in March. In two later works (Calder 1990 [1991a]: 3; Calder & Stephens 1997: 31), Dipleuron Brooks, 1882  was accepted as distinct from Lovenella  based on characters such as the unusual morphology of the stems of the hydroid, being segmented by variably spaced nodes rather than annulated, and the lack of a crease at the base of the operculum. Pires-Miranda et al. (2013), in a study of specimens identified as L. gracilis  from Brazil, upheld the synonymy of the two genera. Although unresolved issues remain in the taxonomy and nomenclature of this and other lovenellids, current usage of the binomen L. gracilis  for the species has been maintained here, following Cairns et al. (1991, 2002).

A long-held belief that Lovenella  is closely related to Eucheilota McCrady, 1859  (e.g., Russell 1953; Kramp 1961) is supported, at least in part, by preliminary molecular studies ( Maronna et al. 2016). However, such results also suggest that both Lovenella  and Eucheilota  as presently constituted may be polyphyletic, and diagnoses of these genera likely need revision. Morphological and molecular studies of their type species ( L. clausa  and Eucheilota ventricularis McCrady, 1859  ), based on topotypic material, are needed. Critically, no hydroid has yet been linked to E. ventricularis  , a major limitation in definitive characterization of Eucheilota  and in overall understanding of both genera. Another taxonomic question needing resolution is whether populations of hydroids assigned to L. gracilis  from the open coast, especially those attached to shells of the bivalve Donax  and other substrates along sandy ocean shores, are conspecific with those from estuarine areas such as the tributaries of Chesapeake Bay.

The medusa known as Dipleuron parvum  (= L. gracilis  ) has been assigned by some authors to the genus Eucheilota  , and to the synonymy of E. duodecimalis L. Agassiz, 1862  ( Mayer, 1910b, as E. duodecimalis  var. par- vum; Allwein 1967, as E. duodecimalis  ). However, life cycle studies ( Calder 1971) have shown that the number of marginal vesicles in medusae of L. gracilis  is indefinite, as currently stated in diagnoses of Lovenella  , rather than fixed, as in Eucheilota  ( Russell 1953; Kramp 1961; Bouillon et al. 2006). For that reason, conclusions that the species is fully conspecific with or constitutes only a variety of E. duodecimalis  has not been adopted here. Allwein (1967: 127) reported finding both E. duodecimalis  and E. duodecimalis var. parvum  (= L. gracilis  ) in the plankton at Beaufort, North Carolina.

A number of hydroids from other geographic regions resemble L. gracilis  , particularly in the peculiar segmentation of the hydrocaulus. One of these, Clytia bakeri Torrey, 1904  , was found on bivalves in the surf zone at Pacific Beach near San Diego, California. Its medusa stage, described by Torrey (1909) as Phialium bakeri  , is much like that of L. gracilis  . No operculum was noted in the original description of the hydroid by Torrey (1904), but the species cannot be assigned to Clytia Lamouroux, 1812  or any other campanularioid genus given the characters of its medusa stage. Hydrothecal margins were said to have been damaged, and Huvé (1952) and Calder (1971) speculated that opercula may have been lost in Torrey’s material. The species was assigned to Eucheilota  by Cairns et al. (1991), but returned to Lovenella  by Cairns et al. (2002). It was discussed as Eucheilota bakeri in Mills et al. (2007)  . Molecular studies reveal a particularly close genetic relationship of the species to hydroids identified as L. gracilis ( Maronna et al. 2016)  , and the two are almost certainly congeneric. Another hydroid resembling L. gracilis  was described as Gonothyraea  (?) nodosa  by Stechow (1914) from Rio de Janeiro, Brazil. Pires-Miranda et al. (2013) were uncertain of its taxonomic status, but Oliveira et al. (2016) included it in the synonymy of L. gracilis  . Meanwhile, L. nodosa Fraser, 1938a  , originally described from Ecuador ( Santa Elena Bay) and the Pacific coast of Mexico (off Morro de Petatlan, Tenacatita Point; Isabel Island; off Thurloe Point), differs from L. gracilis  in having hydrocauli with fewer nodes and much deeper hydrothecae. Lovenella corrugata Thornely, 1908  , from 20 fathoms (37 m) off Khor Shin‘ab, along the Red Sea coast of Sudan, has a hydrocaulus with neither annulations nor nodes. Its hydrothecae are distinct in being relatively deep and cylindrical, with corrugated walls.

Several other species with hydroid stages currently or recently assigned to Lovenella  differ from L. gracilis  in having hydrocauli with annulations or sinuous constrictions rather than cylindrical internodes [ L. clausa ( Lovén, 1836)  from NW Europe; L. briggsi Mulder & Trebilcock, 1915  from Australia; L. rugosa Fraser 1938b  from the Pacific coast of Mexico; L. chiquitita Millard, 1957  from South Africa] or much deeper hydrothecae ( L. grandis Nutting, 1901  ). Two species of hydroids until recently included in Lovenella  by some authors are now assigned to other genera after their polyp and medusa stages were linked in DNA barcoding studies by Schuchert et al. (2017). Firstly, the hydroid L. panicula (G.O. Sars, 1874)  and the medusa Foersteria quadrata Hosia & Pagès, 2007  were found to be stages of the same species. The name Earleria quadrata ( Hosia & Pagès, 2007)  was applied to the species by Schuchert et al., but the binomen Earleria panicula (G.O. Sars, 1874)  has nomenclatural priority. Secondly, the hydroid Lovenella producta (G.O. Sars, 1874)  and the medusa Cyclocanna welshi Bigelow, 1918  were shown to be conspecific, with Cyclocanna producta  becoming the valid name of the species. Hydroids of both species differ significantly from those of L. gracilis  in the morphology of their hydrothecae and hydrocauli. The taxonomy of hydroid and medusa species that have been assigned to Lovenella  has been updated in WoRMS, and the characters of most have been summarized in Pires-Miranda et al. (2013).

The reported range of L. gracilis  in the western North Atlantic extends from southern New England ( Calder 1975) to the southern Caribbean Sea ( Wedler 1975; Bandel & Wedler 1987), and includes the Gulf of Mexico ( Calder & Cairns 2009). It has also been identified as far south as Brazil in the western South Atlantic ( Oliveira et al. 2016). Hydroids identified as Lovenella gracilis  from the Caribbean Sea by Wedler (2017b) are shown with distinct crease lines at the base of the opercula, and his specimens appear more like L. grandis  in that character. Their identity is regarded here as doubtful, bringing those reported by Wedler (1975) and Bandel & Wedler (1987) into question as well.

Fewkes (1891) included L. gracilis  in a guide to invertebrates of New England. No collection data were provided on the species in that work, and it is unclear whether specimens were ever collected by him in the New England region or elsewhere. The account has been excluded from the distribution records below. Lovenella gracilis  was reported from a depth of 16 fathoms (29 m) off Cape Hatteras by Fraser (1944), but the identification is considered questionable. To the south in South Carolina (Calder, unpublished), hydroids largely indistinguishable from L. gracilis  were found in the lower intertidal zone of sandy beaches on bivalve molluscs ( Mulinia lateralis  ) and adhering barnacles (ROMIZ B1551). Farther north, specimens of the species were found on coquina clams ( Donax variabilis  ) at Avalon, New Jersey ( Fig. 9gView FIGURE 9). Other specimens (ROMIZ B1546) generally resembling the species, from Bulls Bay, South Carolina (32°55.9’N, 79°36.2’W), were unusual in being exceptionally large (up to 11 cm high) and profusely branched ( Fig. 9hView FIGURE 9). The identity of the latter hydroids as a possible new species needs to be established. During studies of hydroids from the Chesapeake Bay region, the type locality of L. gracilis  , colonies of the species were reported in shallow waters (1-6 m) from a variety of substrates including algae ( Agardhiella tenera  ), eelgrass ( Zostera marina  ), other hydroids ( Sertularia argentea  ), oyster shells ( Crassostrea virginica  ), and slipper shells ( Crepidula fornicata  ) ( Calder 1971). In southwest Florida during this investigation, specimens were found on turtle grass ( Thalassia testudinum  ), manatee grass ( Syringodium filiforme  ) and dead sand dollars ( Mellita quinquiesperforata  ). Hydroids of the species were found active in the Chesapeake region from late April through late October over a temperature range of 15-27° C, and medusa production was observed from July through October. Interactions between hydroids identified as L. gracilis  and bivalve molluscs, and especially coquina clams ( Donax  ) on sandy beaches, have been explored in studies such as those of Manning and Lindquist (2003) and Dougherty & Russell (2005).

Reported distribution. Gulf coast of Florida. Cape San Blas area ( Shier 1965: 42 (part))  .

Elsewhere in western North Atlantic. USA: Chesapeake Bay, 3–10 ftm (5–18 m) ( Clarke 1882).— USA: North Carolina, Beaufort (medusa) ( Brooks 1882: 140, as Dipleuron parvum  ).— USA: North Carolina, off Cape Fear (medusa) ( Mayer 1910b: 284, as Eucheilota duodecimalis var. parvum  ).—? USA: Massachusetts, Woods Hole, surface tow ( Fraser 1912a: 45, as Lovenella clausa  ).— USA: Mississippi, off Horn Island, on clam shell ( Fincher 1955: 92).— USA: North Carolina, Beaufort area (medusa) ( Allwein 1967: 127, as Eucheilota duodecimalis  (part)).— USA: Virginia, York River (Ellen Island, Perrin, Gloucester Point, Page’s Rock, Bell Rock) + James River (Hampton Flats) ( Calder 1971: 62).— USA: Delaware, Indian River Bay ( Watling & Maurer 1972: 648).— USA: Texas, off Galveston, 3–6 ftm (5–11 m) ( Defenbaugh & Hopkins 1973: 92, as Lovenella  new species).— USA: Massachusetts, Cape Cod Bay, off Provincetown + Jeremy Point, Wellfleet ( Calder 1975: 298).—? Colombia: Santa Marta area, on gastropod shells, sandy substrates ( Wedler 1975: 336; Bandel & Wedler 1987: 41).— USA: Delaware, Indian River ( Maurer 1977: 597).— USA: South Carolina, exposed beaches (on shells of Donax  and Mulinia  ) + higher salinity regions of estuaries (on shells of Crassostrea  ) ( Calder & Hester 1978: 90, as (?) Lovenella gracilis  ).— USA: South Carolina, sandy beaches near Murrells Inlet, on Donax ( Knott et al. 1983: 585)  .— USA: South Carolina, Huntington Beach ( Fox & Ruppert 1985: 38).— USA: Georgia: St. Catherines Island, Engineer Point + Middle Beach + North Beach + Picnic Point + Seaside Delta ( Prezant et al. 2002: 8).— USA: New Jersey, Seaside Park, sandy beach, on Donax ( Manning & Lindquist 2003: 416)  .— USA: North Carolina, Pine Knoll Shores, sandy beaches, on Donax ( Manning & Lindquist 2003: 416)  .— USA: New Jersey, sandy beaches, on Donax, Sea Isle City  , 39°12.9’N, 74°70.7’W + Avalon, 39°07.3’N, 74°74.0’W + museum specimens: Atlantic City (from ~1886) + Wildwood (from 1900) + Sea Isle City (from 1901) + Avalon (from 1962) ( Dougherty & Russell 2005: 35, 37).— USA: Delaware, on Donax  , museum specimens Indian River Inlet (from 1965) ( Dougherty & Russell 2005: 35, 37).— USA: New Jersey, Wildwood Crest ( Govindarajan et al. 2006: 824).—?Caribbean Sea ( Wedler 2017b: 119, figs. 114A–D).

Kingdom

Animalia

Phylum

Cnidaria

Class

Hydrozoa

Order

Leptothecata

Family

Lovenellidae

Genus

Lovenella

Loc

Lovenella gracilis Clarke, 1882

Calder, Dale R. 2019
2019
Loc

Lovenella gracilis Clarke, 1882: 139

Shier, C. F. 1965: 42
Clarke, S. F. 1882: 139
Loc

Lovenella gracilis

Shier, C. F. 1965: 42
Joyce, E. A. Jr. 1961: 61