Lovenellidae
Encyclopedia
The Lovenellidae are a hydrozoa
n family
of the suborder Conica
. Their hydroid
s live together in upright stolon
al or sympodial
colonies, and their gonophores are pedunculate free-roaming medusa
e.
The relationships of this fairly small but distinctive radiation
to other conican Leptomedusae
are not well understood at present. The Haleciidae
have served as a "wastebin taxon
" for unidentifiable medusae; they contained several species that have been identified as gonophores of Lovenellidae, and as per standard practice have been moved to the hydroids' family.
to bell-shaped hydrothecae are pedicellate. They have a diaphragm
and a conical operculum
apical
ly to the hydrothecal wall, formed either by this wall or by separated embayments of the hydrothecal margin, with a lining of triangular plates. The tentacles of some but not all carry webbing between them. The hydrothecae wear down during the individual hydroids' life, and old ones often have just the collar-like bottom of the hydrotheca remaining.
The manubrium
of the medusa
e is short. They lack a gastric peduncle, ocelli (making them effectively blind) and excretory pores, and have 4 simple radial canals and in adults at least 16 statocyst
s. The tentacles at their margin are hollow and at the side carry cirri
; cirri are lacking from around the margin however. The gonads are located at the radial canals; they do not reach the manubrium.
of Lovenellidae are generally recognized as valid if Cirrholovenia and Eucheilota are merged therein, as is widely done these days. Hydranthea is placed here in some treatments, but otherwise in the Haleciidae
; corroborating the relationship between these two hard-to-place families:
Hydrozoa
Hydrozoa are a taxonomic class of very small, predatory animals which can be solitary or colonial and which mostly live in saltwater. A few genera within this class live in freshwater...
n family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of the suborder Conica
Conica (Hydrozoa)
Conica are a cnidarian suborder of the Leptomedusae . They make up the bulk of their order; their internal relationships are not well resolved, and most of the roughly 30 families are not yet assigned to a superfamily....
. Their hydroid
Hydroid
-Marine biology:Hydroids are a life stage for most animals of class Hydrozoa, small predators related to jellyfish.-Botany:In mosses, hydroids form the innermost layer of the stem of long, colourless, thin walled cells of small diameter.The cells are dead and lack protoplasm.They function as water...
s live together in upright stolon
Stolon
In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...
al or sympodial
Sympodial
Sympodial means "with conjoined feet", and in biology is often used to refer to the outward morphology or mode of growth of organisms.-In botany:...
colonies, and their gonophores are pedunculate free-roaming medusa
Medusa (biology)
In biology, a medusa is a form of cnidarian in which the body is shaped like an umbrella, in contrast with polyps. Medusae vary from bell-shaped to the shape of a thin disk, scarcely convex above and only slightly concave below...
e.
The relationships of this fairly small but distinctive radiation
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...
to other conican Leptomedusae
Leptomedusae
Leptomedusae or Leptomedusa, commonly called thecate hydroids, are a cnidarian order in the subclass Leptolinae. They were formerly placed at suborder rank in the paraphyletic "Hydroida"...
are not well understood at present. The Haleciidae
Haleciidae
The Haleciidae are a hydrozoan family of the suborder Conica. Their hydroid colonies emerge from a creeping hydrorhiza and usually form upright branching colonies; some species' colonies are stolonal though. Their gonophores are typically sporosacs, growing singly or bunched into a glomulus...
have served as a "wastebin taxon
Wastebin taxon
Wastebasket taxon is a term used in some taxonomic circles to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined by their lack of one or more distinct character states or by their not belonging to one or more other taxa...
" for unidentifiable medusae; they contained several species that have been identified as gonophores of Lovenellidae, and as per standard practice have been moved to the hydroids' family.
Description
The elongated, everted-conicalCone (geometry)
A cone is an n-dimensional geometric shape that tapers smoothly from a base to a point called the apex or vertex. Formally, it is the solid figure formed by the locus of all straight line segments that join the apex to the base...
to bell-shaped hydrothecae are pedicellate. They have a diaphragm
Diaphragm
-Optics and photography:* Diaphragm , a stop in the light path of a lens, having an aperture that regulates the amount of light that passes* Diaphragm shutter, a type of leaf shutter consisting of a number of thin blades in a camera-Acoustics:...
and a conical operculum
Operculum
Operculum may refer to:*Operculum , a stiff structure resembling a lid or a small door that opens and closes**Operculum , a lid on the shell of some gastropods**Operculum , a lid on the orifice of some bryozoans...
apical
Apical
Apical, from the Latin apex meaning to be at the apex or tip, may refer to:*Apical , an anatomical term of location for features associated with the base of an organism or structure...
ly to the hydrothecal wall, formed either by this wall or by separated embayments of the hydrothecal margin, with a lining of triangular plates. The tentacles of some but not all carry webbing between them. The hydrothecae wear down during the individual hydroids' life, and old ones often have just the collar-like bottom of the hydrotheca remaining.
The manubrium
Manubrium
The manubrium or manubrium sterni is the broad, upper part of the sternum. Located ventrally with a quadrangular shape, wider superiorly and narrower inferiorly, it articulates with the clavicles and the first two ribs.-Borders:The superior border is the thickest and presents at its center the...
of the medusa
Medusa (biology)
In biology, a medusa is a form of cnidarian in which the body is shaped like an umbrella, in contrast with polyps. Medusae vary from bell-shaped to the shape of a thin disk, scarcely convex above and only slightly concave below...
e is short. They lack a gastric peduncle, ocelli (making them effectively blind) and excretory pores, and have 4 simple radial canals and in adults at least 16 statocyst
Statocyst
The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, cnidarians, echinoderms, cephalopods, and crustaceans. A similar structure is also found in Xenoturbella. The statocyst consists of a sac-like structure containing a mineralised mass and numerous...
s. The tentacles at their margin are hollow and at the side carry cirri
Cirrus
Cirrus may refer to:In science:*Cirrus cloud, a type of cloud*Cirrus , a German research rocket*Cirrus, a fleshy, downward extension of the upper lip in salamanders or fish*Cirrus, a thoracic limb of an adult barnacle...
; cirri are lacking from around the margin however. The gonads are located at the radial canals; they do not reach the manubrium.
Genera
Five generaGenera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
of Lovenellidae are generally recognized as valid if Cirrholovenia and Eucheilota are merged therein, as is widely done these days. Hydranthea is placed here in some treatments, but otherwise in the Haleciidae
Haleciidae
The Haleciidae are a hydrozoan family of the suborder Conica. Their hydroid colonies emerge from a creeping hydrorhiza and usually form upright branching colonies; some species' colonies are stolonal though. Their gonophores are typically sporosacs, growing singly or bunched into a glomulus...
; corroborating the relationship between these two hard-to-place families:
- Cirrholovenia Kramp, 1959
- Eucheilota McCrady, 1859
- Lovenella Hincks, 1868
- Mitrocomium Haeckel, 1879 (= Haleciella)
- Paralovenia