Lampanella minima, (GMELIN 1791)

Strong, Ellen E., 2003, Refining molluscan characters: morphology, character coding and a phylogeny of the Caenogastropoda, Zoological Journal of the Linnean Society 137 (4), pp. 447-554 : 458-459

LAMPANELLA MINIMA (GMELIN 1791)

Material Examined

Missouri Key, Florida ( USNM 890934 ) .

External anatomy and mantle cavity

Propodium bearing deep opening to anterior pedal gland. Operculum corneous, thin, multispiral with central nucleus. Mantle margin papillate with short, thin, widely spaced papillae arising just inside mantle rim ( Fig. 6B ). Inhalant margin marked by scalloping of mantle edge; exhalent margin thickened, and bearing two papillae ( Fig. 6B ). Hypobranchial gland well developed.

Reproductive system

Gonad spreading dorsally over digestive gland to posterior end of midgut. Renal oviduct contacting pericardium ( Fig. 2A , per); gonopericardial canal absent. Oviduct discharging to glandular pallial oviduct at base of mantle cavity. Pallial oviduct open along entire length, composed of lateral (inner) and medial (outer) laminare, with deep intervening oviductal groove. Medial lamina edge bearing deep, ciliated sperm gutter, running from distal tip and terminating short distance before base of mantle cavity. Large spermatophore bursa (spb) dorsally overlying broad, flat seminal receptacle (rcs) embedded in albumen gland (ag) of medial lamina. Bursa and receptacle communicating posteriorly via narrow, ciliated duct and opening to sperm gutter anteriorly, with broad aperture of bursa just anterior to narrow receptacle aperture. Degenerating spermatophores commonly found within bursa. Shallow, ciliated groove traversing side of foot from tip of pallial oviduct to ovipositor.

Straight distal vas deferens swollen with ripe sperm, functioning as seminal vesicle. Renal vas deferens narrowing shortly behind base of mantle cavity, contacting pericardium with connective tissue, but gonopericardial canal absent ( Fig. 3A , per). Vas deferens opening to prostate (pr) at base of mantle cavity, composed of parallel, glandular laminae with deep intervening groove. Free edge of medial lamina with low, longitudinal, glandular ridge running along inner border. Tissue of medial lamina forming deep transverse cleft, comprising spermatophore forming organ ( Fig. 3A ). Glandular tissue of lateral lamina extending short distance onto pallial floor at base of mantle cavity ( Fig. 3A ).

Alimentary system

Foregut. Radula taenioglossate. Paired jaw present at anterior end of dorsal folds; jaw composed of rods with laterally overlapping homogeneous layer. Subradular membrane incompletely covering odontophore. Subradular organ present, comprising broad, glandular shield with transverse ridges ( Fig. 4D ). Radular sac long and somewhat coiled, lying alongside midoesophagus. Tube-like salivary glands ( Fig. 6B , sgl) passing through circum-oesophageal nerve ring. Ventral fold present ( Fig. 8D , vf), running length of anterior oesophagus and terminating at initiation of oesophageal gland. Paired ventro-lateral folds ( Fig. 9D , vlf) emerging within posterior most buccal cavity, at inner aspect of two lateral outpocketings (bp) lined with acidophilic epithelium. Weakly glandular, septate oesophageal gland present ( Fig. 6B , eg) within enlarged mid-oesophagus, composed of bilaterally symmetrical septate folds and an open, ventral food groove. Septae terminating short distance before end of mid-oesophagus; posterior mid-oesophagus comprising short, crop-like compartment.

Midgut. Oesophagus entering midgut ventrally on left ( Fig. 13B, e ). Well-developed sorting area (sa), extending posteriorly from intestinal groove, past oesophageal aperture, along floor and wall of gastric chamber. Ciliated fold (cf) V-shaped, forming margin of sorting area, extending anteriorly from oesophageal aperture to intestinal groove, then turning posteriorly. Ciliary currents flowing toward intestinal groove within sorting area. Hypertrophied glandular pad (gp) with median groove, extending to base of gastric chamber. Single digestive gland duct (dgd) lying to left of glandular pad, posterior to oesophageal aperture. Ventro-lateral gastric shield (gs) present. Style sac region with transversely folded epithelium and welldifferentiated cilia. Crystalline style present. Broad, raised ciliary tract (ctr) present along inner (style sac) edge of major typhlosole (t1). Currents flowing clockwise within style sac region when viewed from behind.

Hindgut. Intestine exiting style sac, turning posteriorly alongside style sac to gastric chamber, then turning anteriorly.

Reno-pericardial system

Kidney partially overlying pericardium, extending into pallial roof. Weakly developed nephridial gland present. Reno-pericardial canal opening ventrally, just behind mantle cavity. Afferent renal vessel entering kidney adjacent to reno-pericardial canal, continuing dorsally, ramifying into tubules within roof.

Nervous system and sensory structures

Nervous system epiathroid ( Fig. 24B ), right and left dialyneurous, lying just behind buccal mass ( Fig. 6B , nr). Small buccal ganglia lying at back of buccal mass just in front of cerebral ganglia. Single, large tentacular nerve (tn) with several small branches, one innervating snout and others innervating tentacle. Supra-oesophageal (sp) and sub-oesophageal ( Fig. 24B , sb) connectives long. Single visceral ganglion ( Fig. 6B , vg) overlying oesophagus at posterior end of cephalic haemocoel, under pericardium. Statocysts with numerous statoconia ( Fig. 24B , sc), present on postero-dorsal surfaces of pedal ganglia. Osphradium ( Fig. 6B , os) forming long, narrow ciliated ridge, approximately two-thirds length of ctenidium.

Remarks

Histological sections revealed that Lampanella minima ( Fig. 9D ) possesses glandular expansions of the anterior most oesophagus (bp) that are similar in position (below the dorsal folds (df), adjacent to the buccal ganglia (bg)) and histological detail (strongly acidophilic – unlike the basophilic foregut epithelium of other caenogastropods) to the buccal pouches of Littorina littorea . Thus, although buccal pouches have been reported only rarely ( Melanopsis praemorsa ; Graham, 1939; Thiara amarula , Melanatria fluminea ; Starmühlner, 1969) or as lacking entirely within the superfamily ( Houbrick, 1988), these structures are interpreted here as homologous to the buccal pouches of other caenogastropods.

Discussion

The reproductive anatomy of Lampanella minima differs from other batillariids ( Houbrick, 1988) in the absence of baffles on the lateral lamina and the presence of a sperm gutter only along the medial lamina, and not along the lateral lamina.

The mid-oesophagus of cerithioideans displays a range of morphologies from a simple crop to a welldeveloped septate oesophageal gland ( Graham, 1939; Starmühlner, 1969; Houbrick, 1988). The gut of Lampanella minima and other batillariids is intriguing in the presence of a crystalline style in conjunction with an oesophageal gland; a rare co-occurrence among caenogastropods (e.g. Graham, 1939). The midgut of L. minima shares many features with other marine cerithioideans, including the presence of a single digestive gland duct, the crystalline style and hypertrophied gastric pad ( Graham, 1939; Marcus & Marcus, 1964; Driscoll, 1972; Houbrick, 1974, 1987, 1988, 1991a,b).

The renal organ remains under-represented in descriptions of cerithioidean taxa. Often the presence of the nephridial gland is neither confirmed nor rejected (e.g. Marcus & Marcus, 1964; Houbrick, 1987; Ponder, 1991). Some studies have implied the presence of the gland, figuring a narrow strip of tissue adjacent to the pericardium ( Houbrick, 1991a) or a large lobe nearly equal in size to the remaining kidney tissue ( Houbrick, 1974). Yet others have stated explicitly that the nephridial gland is absent ( Simroth, 1896 – 1907; Seshaiya, 1934b; Strong & Glaubrecht, 2002). Thus, it appears that presence or absence and development of the gland varies within the group, but the limited information available renders it difficult to evaluate in a comparative context.

The nervous system of Lampanella minima is right and left dialyneurous, congruent with studies of batillariids and other cerithioidean families including the Melanopsidae , Pleuroceridae , Potamididae and Cerithideidae ( Bouvier, 1887; Marcus & Marcus, 1964; Houbrick, 1988).

Figures

Figure 2. Female reproductive morphology. (A) Lampanella minima. Note connective tissue between renal oviduct and pericardium. (B) Crepidula plana. (C) Petaloconchus varians. (D) Strombus mutabilis. Note egg groove from capsule gland down side of foot. Dotted line indicates double-groove portion of albumen gland. (E) Cypraea robertsi. Note duct of receptacle at posterior end of albumen gland. (F) Panarona clavatula. (G) Prunum apicinum. Note that base of mantle cavity lies between the capsule and albumen glands. (H) Urosalpinx cinerea. Ventro-lateral lobe of capsule gland is shown by transparency. Note blind diverticulum off renal oviduct and small aperture connecting vestibule and bursa copulatrix. Base of mantle cavity indicated by arrow. (I) Ilyanassa obsoletus. Note shallow pocket in distal end of capsule gland, perhaps functioning as bursa. Scale bar = 1 mm. Abbreviations: ag, albumen gland; bc, bursa copulatrix; cg, capsule gland; fo, female opening; gpc, gonopericardial canal; igl, ingesting gland; mc, base of mantle cavity; per, pericardium; rcs, seminal receptacle; spb, spermatophore bursa; u, uterine ball; v, vagina.

Figure 3. Male reproductive morphology. (A) Lampanella minima. Note connective tissue between renal vas deferens and pericardium and accessory lobe of prostatic tissue on mantle cavity floor alongside proximal prostate. (B) Petaloconchus varians. (C) Crepidula plana. Note terminal papilla. (D) Strombus mutabilis. Note seminal groove continuous along ventral aspect of penis. (E) Cypraea robertsi. Note seminal groove continuous along ventral aspect of penis. (F) Prunum apicinum. Penial duct not shown. Arrow indicates slit-like communication between proximal prostate and mantle cavity. (G) Ilyanassa obsoletus. Arrow indicates fused, tube-like communication between proximal prostate and mantle cavity. Scale bar = 1 mm. Abbreviations: ped, penial duct; pe, penis; per, pericardium; pr, prostate; pvd, pallial vas deferens; sg, seminal groove.

Figure 4. Morphology of odontophore; subradular organ (indicated by arrows). Except when noted, view is from the side and ventral is to the right. (A) Theodoxus fluviatilis, ventral view. Subradular organ absent. Scale bar = 100 Mm. (B) Neocyclotus dysoni ambiguum. Scale bar = 1 mm. (C) Marisa cornuarietis. Scale bar = 1 mm. (D) Lampanella minima. Scale bar = 100 Mm. (E) Littorina littorea. Scale bar = 100 Mm. (F) Neverita duplicata. Scale bar = 100 Mm. (G) Cypraea robertsi. Subradular organ absent. Scale bar = 1 mm. (H) Panarona clavatula. Ventral is down. Scale bar = 100 Mm.

Figure 6. Morphology of cephalic haemocoel among basal caenogastropods. (A) Neocyclotus dysoni ambiguum. For simplicity, large salivary glands removed. Scale bar = 1 mm. (B) Lampanella minima. Scale bar = 1 mm. (C) Cypraea robertsi. For simplicity, large salivary glands removed. Scale bar = 1 mm. (D) Bithynia tentaculata. Scale bar = 0.5 mm. (E) Crepidula plana. Scale bar = 1 mm. Abbreviations: bp, buccal pouch; d, dialyneury; e, oesophagus; eg, oesophageal gland; nr, circum-oesophageal nerve ring; os, osphradium; osg, osphradial ganglion; ps, proboscis sheath; sb, sub-oesophageal ganglion; sgd, salivary gland duct; sgl, salivary glands; sp., supra-oesophageal ganglion; tn, tentacular nerve; vg, visceral ganglion; z, zygoneury.

Figure 8. Histology of anterior oesophagus; ventral fold. (A) Macleaniella moskalevi. Scale bar = 0.5 mm. (B) Theodoxus fluviatilis. Scale bar = 0.5 mm. (C) Neocyclotus dysoni ambiguum. Scale bar = 0.5 mm. (D) Lampanella minima. Scale bar = 1 mm. (E) Strombus mutabilis. Scale bar = 0.5 mm. (F) Littorina littorea. Scale bar = 0.5 mm. (G) Cypraea robertsi. Note that ventral fold is offset to the right. Scale bar = 0.5 mm. Abbreviations: bp, buccal pouch; bg, buccal ganglion; c., radular cartilage; ceg, cerebral ganglion; df, dorsal fold; e.g. oesophageal gland; r, radula; sgd, salivary gland duct; sgl, salivary gland; vf, ventral fold; vlf, ventro-lateral fold.

Figure 9. Histology of anterior oesophagus; ventro-lateral folds. (A) Macleaniella moskalevi. Scale bar = 0.5 mm. (B) Theodoxus fluviatilis. Scale bar = 0.5 mm. (C) Neocyclotus dysoni ambiguum. Scale bar = 0.5 mm. (D) Lampanella minima. Scale bar = 1 mm. (E) Strombus mutabilis. Scale bar = 0.5 mm. (F) Crepidula plana. Scale bar = 1 mm. (G) Bithynia tentaculata. Scale bar = 1 mm. (H) Littorina littorea. Scale bar = 0.5 mm. Abbreviations: bp, buccal pouch; bg, buccal ganglion; ca, radular cartilage; ceg, cerebral ganglion; df, dorsal fold; e, oesophagus; r, radula; sgl, salivary gland; vf, ventral fold; vlf, ventro-lateral fold.

Figure 13. Midgut morphology. White arrows indicate direction of ciliary currents. (A) Neocyclotus dysoni ambiguum, dorsal view. (B) Lampanella minima, dorsal view. Scale bar = 1 mm. Abbreviations: cf, ciliated fold; cs, ciliated strip; ctr, ciliary tract; dgd, digestive gland duct; dv, digestive gland vestibule; e, oesophagus; gap, gastric pouch; gp, glandular pad; gs, gastric shield; pyc, pyloric caecum; sa, sorting area; ss, style sac; t1, major typhlosole; t2, minor typhlosole.

Figure 24. Circum-oesophageal nerve ring morphology. (A) Neocyclotus dysoni ambiguum. Scale bar = 0.5 mm. (B) Lampanella minima. Scale bar = 0.5 mm. (C) Crepidula plana. Scale bar = 0.5 mm. (D) Cypraea robertsi. Upper diagram depicts cerebral, pleural, supra-esophageal, and sub-oesophageal ganglia; lower diagram depicts pedal ganglia and pedal cords. Scale bar = 1 mm. (E) Nitidiscala tinctum. Scale bar = 0.25 mm. (F) Prunum apicinum. Scale bar = 0.5 mm. (G) Ilyanassa obsoletus. Scale bar = 0.5 mm. Abbreviations: bg, buccal ganglion; ceg, cerebral ganglion; d, dialyneury; e, oesophagus; pc, pedal cord; pdg, pedal ganglion; plg, pleural ganglion; ppg, propodial ganglion; sb, sub-oesophageal ganglion; sc, statocone; sp, supra-oesophageal ganglion; z, zygoneury.