Hoffmannola lesliei ( Stearns, 1892 )

Dayrat, Benoît, Zimmermann, Sara & Raposa, Melissa, 2011, Taxonomic revision of the Onchidiidae (Mollusca: Gastropoda: Pulmonata) from the Tropical Eastern Pacific, Journal of Natural History 45 (15 - 16), pp. 939-1003 : 979-987

publication ID	https://doi.org/ 10.1080/00222933.2010.545486
persistent identifier	https://treatment.plazi.org/id/03D887F6-FFC4-FFC8-FE2B-9ABBFDC1B536
treatment provided by	Felipe
scientific name	Hoffmannola lesliei ( Stearns, 1892 )
status

Treatment

Hoffmannola lesliei ( Stearns, 1892) View in CoL

( Figures 19–21 View Figure 19 View Figure 20 View Figure 21 )

Onchidium lesliei Stearns 1892: 87 View in CoL [as Orchidium View in CoL , a spelling mistake of Onchidium View in CoL ].

Watsoniella lesliei . – Hoffmann 1928: 56–68, figs 11–15, plate 4, figs 14–18. — Labbé 1934: 245.

Type material

The three syntypes could not be located. Type locality: Galapagos Islands, Charles Island (one specimen, collected 8 April 1888, US Steamer Albatross) and Albermarle Island (two specimens, collected 10 April 1888, US Steamer Albatross) .

Additional material examined and dissected

A total of 57 specimens was examined, 15 of which were dissected to study their internal anatomy. Examined specimens were collected from nine localities on five of the Galapagos Islands , four islands being new records (see Distribution). Galapagos Islands , Isla San Salvadore [James Island], N end of James Bay , 2 February 1967, three specimens 20/20 (#1) to 14/ 12 mm preserved [leg. I. Wiggins], identified as Onchidiidae [unknown identifier], ( CASIZ 009777 ); Galapagos Islands , Isla Santa Cruz, Academy Bay , January 1974, one specimen 22/ 19 mm preserved [leg. unknown], identified as Hoffmannola lesliei [unknown identifier], ( CASIZ 078708 ) [dissected]; Galapagos Islands , Isla Santa Cruz, Academy Bay , 25 January 1964, three specimens 24/18 (#2) to 18/12 (#1) mm preserved [leg. D.P. Abbott], identified as Hoffmannola lesliei by D.P. Abbott, ( CASIZ 078709 ); Galapagos Islands , Isla Santa Cruz, Academy Bay , 25 January 1964, eight specimens 20/14 to 15/ 12 mm preserved [leg. D.P. Abbott], identified as Onchidiidae by T. M. Gosliner, ( CASIZ 072952 ) [three specimens dissected: 20/14 (#1), 20/17 (#3) and 15/12 (#2)]; Galapagos Islands , Isla Santa Cruz, Academy Bay , 12 February 1964, 18 specimens 28/23 (#1) to 20/20 (#2) mm preserved [leg. A.G. Smith], identified as Hoffmannola lesliei by A.G. Smith, ( CASIZ 078368 ); Galapagos Islands , Garden [possibly for Gardner] Island, [collecting date unknown], 13 specimens 20/18 (#1) to 10/8 (#2) mm preserved [leg. unknown], identified as Onchidium [unknown identifier], ( ANSP A7486 View Materials d) [specimens poorly preserved]; Galapagos Islands , Albemarle Island , Iguana cove, [collecting date unknown], three specimens 25/25 (#1) to 11/ 16 mm preserved [leg. unknown], identified as Onchidium [unknown identifier], ( ANSP 81945 View Materials ) [specimens poorly preserved]; Galapagos Islands , Marborough Island [Isabela], Iguana cove, 26 January 1899, four specimens 25/20 (#1) to 15/12 (#2) mm preserved [leg. unknown], identified as Onchidium lesliei [unknown identifier], ( ANSP 81946 View Materials ) [specimens poorly preserved]; Galapagos Islands, Albemarle Island, three specimens 36/25 (#1) to 15/ 10 mm preserved [leg. USFC Albatross], identified as Onchidium binneyi ? [unknown identifier], ( ANSP 111156 View Materials ) [specimens poorly preserved] .

Distribution.

Endemic to the Galapagos Islands: Santa Maria (= Charles Island, type locality; Stearns 1892); Isabella (= Albemarle, type locality; Stearns 1892; Hoffmann, 1928; present study); San Salvadore (present study); Santa Cruz (present study); Garden [possibly for Gardner] Island (present study); Isabela Island (present study). Labbé (1934) only mentioned H. lesliei from the Galapagos, without new material.

Habitat

Intertidal. On rocks.

Remarks on the original description

The original description, quite short, is reproduced here in its entirety:

Form rounded ovate, nearly as broad as long. Dorsum coriaceum, nearly black, shiny, closely irregularly reticulated, with finely incised lineation, and otherwise characterized by somewhat distant tiatly rounded papillae. Underside, dingy yellowish white; margin of mantle wide, nearly smooth; edge of same simple. Anal opening posterior, near edge of mantle and somewhat produced. Respiratory orifice smaller, in median line with and infront of anus. Sexual orifice anterior on the right side, under the edge of the large oval hood or collar. Labial palpi thin, largely expanded.

Stearns only described the external morphology, which, at the time, was enough to distinguish H. lesliei from all other known onchidiid species, because of the fused oral lobes, which Stearns referred to as the “collar”. However, his description of the position of the male anterior opening is erroneous. As pointed out by Hoffmann (1928), the male opening is median, superior to the oral “collar”.

Description of new specimens

Because the type material could not be located, the description below is based exclusively on non-type specimens.

External Morphology ( Figure 19 View Figure 19 ). Background colour of dorsal notum of live animals brown to blackish, slightly mottled with lighter areas around small papillae. In preserved animals, dorsal colour from homogeneously whitish tan to dark brown. Hyponotum and pedal sole whitish tan or, exceptionally, light brown.

Maximum size of preserved specimens from 36/ 25 mm ( ANSP 81946 #1) to 10/ 8 mm ( ANSP A7486d #2). Body high, not flattened. Hyponotum horizontal. Dorsal notum oval (slightly longer than wide) or round. In most individuals, notum almost smooth to finely granular covered by distant, low, rounded papillae (<1 mm high); papillae more abundant on side of notum than in centre. Margin of notum smooth. Dorsal papillae with dorsal eyes absent. Dorsal gills absent.

In most individuals, total width of hyponotum (left and right sides added) equal to width of pedal sole (H = S). Exceptionally, pedal sole wider than total width of hyponotum (H <S). On hyponotum, hyponotal line around pedal sole separating hyponotum into inner area (close to foot) and outer area. Distance between hyponotal line and pedal sole from one sixth to one third of width of hyponotum (hyponotal line closer to the pedal sole than to hyponotum margin). Openings (pneumostome, male opening and eye tentacles) within area delimited by hyponotal line.

Peripodial groove present on right side, from posterior genital openings (female opening and anus) to opening of pedal gland in buccal area. Anus posterior, close to pedal sole, slightly on right of median line. Anus occasionally median. Posterior female genital opening close to anus. Pneumostome very close to anus, or one third closer to pedal sole than hyponotal margin. Pneumostome elongated and slightly on the right of median line (although exceptionally median). In anterior region, head covered dorsally by notum. Head bears pair of retractile, ocular tentacles, with eyes at tip. In most specimens, tentacles deeply retracted. Left and right oral lobes not distinct (fused medially), superior to mouth, inferior to ocular tentacles. Opening of pedal gland median, inferior to mouth. Male genital opening median, superior to fused oral lobes.

Marginal glands ( Figure 19 View Figure 19 ). From 36 to 44 glands on each side. Glands very close to each other, in approximately three longitudinal rows, and on different frontal planes. Glands from 0.5 to 1 mm in diameter.

Visceral cavity ( Figure 19 View Figure 19 ). In its two posterior thirds, visceral cavity divided by strong, longitudinal septum. Septum attached ventrally to floor of visceral cavity and dorsally to dorsal notum. Heart and part of the digestive system (intestine loop and digestive gland) on right side of septum. Septum divided ventrally into two walls separated by tiny space (retractor muscle inserts between these two walls of septum).

Digestive system ( Figures 19 View Figure 19 and 20 View Figure 20 ). No jaw-like structure present on surface of oral tube. Left and right salivary glands heavily branched, join buccal mass dorsally, on either side of oesophagus. Radula in between two large postero-lateral muscular masses. Radular maximum size 10/ 6 mm, when flattened. Each radular row with one rachidian tooth and two half rows of lateral teeth of similar size and shape (except first and second inner lateral teeth). Radular formulae vary among individuals ( Table 2). From 85 to 160 rows, and from 150 to 515 teeth per half row. No strict correlation between size of specimens and radular formulae. Rachidian tooth tricuspid: median cusp always present; two lateral cusps on two lateral branches of base of rachidian tooth may be absent (especially in small rachidian teeth). Rachidian teeth slightly smaller than lateral teeth: total length of base of rachidian tooth <40 µm, median cusp ∼ 10 µm in length. Posterior-lateral aspect of base of rachidian teeth only slightly concave. Half rows of lateral teeth at an angle of aproximiately 45 ◦ to rachidian axis. Lateral teeth characterized by base attached to radular membrane, with dorsal, strong, flattened hook at 45 ◦ angle to radular membrane; triangular structure between base and hook supports hook but does not reach tip. Length of dorsal hook usually is ∼ 20 µm and <40 µm. Also, smaller (<10 µm) pointed cusp on outer, lateral expansion of base. In most cases, lateral cusp cannot be observed on SEM picture because hidden below hook of adjacent, outer tooth; however, lateral cusps conspicuous when teeth not too close (such as in the innermost and outermost regions). With exception of first two to five innermost lateral teeth, size of lateral teeth does not vary across half row, nor does it among half rows. Shape of tip of hook from truncate to rounded, varies among individuals and between rows of same radula. Hooks not straight, slightly curved inward. Finally, half rows at a 45 ◦ angle to rachidian axis, but hooks almost parallel to rachidian axis.

Oesophagus narrow and straight at proximal end but enlarges into wide crop covering almost entire posterior end of buccal mass. Oesophagus enters stomach anteriorly, close to connection of stomach with dorsal and lateral lobes of digestive gland. Only small portion of posterior aspect of stomach can be seen in dorsal view, because largely covered by three lobes of digestive gland: dorsal lobe mainly located on right aspect of visceral mass; left, lateral lobe mainly ventral; posterior lobe covers posterior aspect of visceral mass. U-shaped sac stomach divided into three chambers: first chamber, delimited by a thin layer of tissue, receives oesophagus and ducts of dorsal and left lateral lobes of digestive gland; second chamber, posterior, delimited by thick muscular tissue and receives duct of posterior lobe of digestive gland; third chamber delimited by thin layer of tissue; in some individuals, third chamber funnel-shaped. No strong ridges on internal surface of stomach. Intestine long, narrow, and of type IV ( Labbé, 1934). No rectal gland.

Nervous system ( Figure 19 View Figure 19 ). Central nervous system densely compact, often embedded and protected within layer of connective tissue. Circum-oesophageal nerve ring post-pharyngeal. Two cerebral ganglia not fused, separated by short commissure. Pleural and pedal ganglia distinct. Cerebro-pleural and pleuro-pedal connectives very short: pleural, cerebral, and pedal ganglia touch each other. Visceral loop very short, and visceral ganglion touches both left and right pleural ganglia. Nerves from cerebral Note: H = hyponotum total width (left and right); S = pedal sole width; radular formula format as range of rows × (range of number of left lateral teeth per half row – one rachidian tooth – range of number of left lateral teeth per half row); patterns of attachment of retractor muscle follows Plate’s (1893) classification.

ganglia innervate buccal area and ocular tentacles, and male anterior genital organs (penial complex) on right side. Nerves from pedal ganglia innervate foot. Nerves from pleural ganglia innervate lateral and dorsal regions of mantle. Nerves from visceral ganglia innervate visceral organs.

Pallial complex ( Figure 19 View Figure 19 ). Heart enclosed in pericardium, located on right portion of visceral cavity, i.e. on right side of septum. Large anterior ventricle becomes large aorta that branches into smaller vessels delivering blood to visceral organs. Posterior auricle significantly smaller than ventricle. Pericardium communicates through small hole with right portion of renal-pulmonary complex. Kidney intricately attached to pulmonary cavity and forms two, left and right, parts, left part significantly longer than right part (length of left pulmonary cavity about same as that of septum). Pulmonary cavity characterized by complex folds of internal lining, likely to increase tissue surface participating in gas exchange.

Reproductive system: posterior parts ( Figure 21 View Figure 21 ). Hermaphroditic gland forms single mass sub-divided into acini. Hermaphroditic duct highly-coiled, conveys gametes (eggs and autosperm) up to spermoviduct. Small branch of hermaphroditic duct goes directly to female gland mass. Another branch of hermaphroditic duct leads to small, coiled, finger-shaped pouch (receptaculum seminis = vesicula seminalis). From receptaculum seminis, narrow duct goes back toward female gland mass (mucous and albumen glands with ducts opening near where hermaphroditic duct becomes spermoviduct). Proximal spermoviduct embedded within the female gland mass and not divided, at least externally. Prostate not distinct externally may be within walls of spermoviduct or vas deferens. Distally, male and female ducts separate: vas deferens conveys autosperm up to cephalic region; free oviduct conveys eggs up to female opening and exosperm from female opening up to fertilization chamber, near proximal end of spermoviduct. Distally, oviduct becomes vagina. Spherical spermatheca (which stores exosperm) connects to distal region of oviduct through short duct. Short, accessory, vaginal gland opens into distal portion of oviduct.

Reproductive system: male, anterior parts ( Figure 21 View Figure 21 ). No accessory penial gland. No distinct penis inside penial sheath. No papilla at distal end of deferens duct. Penial sheath not covered internally by folds. Penial sheath <500 µm in diameter and 6 mm in length. No caecum and no concretions in penial sheath. Deferent duct loosely convoluted (fewer than 10 loops) from entrance in visceral cavity up to where it joins penial apparatus. Number of loops varies among individuals. Diameter of deferent duct more or less constant along its whole length (∼ 200 µm maximum). After it joins penial sheath, deferent duct does not directly join male opening but forms several loops inside proximal portion of penial sheath, makes U-turn, and then goes back distally toward male opening. Retractor muscle anchors on penial sheath near where deferent duct makes a U-turn inside penial sheath, and inserts in between two walls of septum, close to floor of visceral cavity. Retractor muscle very thin, inconspicuous, even missing in many specimens.

Discussion

Prior to the present study, the internal anatomy was only described by Hoffmann (1928), based on material from only one locality. Hoffmann provided a detailed description of the septum dividing the visceral cavity, based on a series of drawings of transversal cuts of the body. Generally speaking, his description is quite detailed and long. However, most systems were not illustrated, which makes the description difficult to read: the drawings of the radular teeth, penial sheath and posterior genital organs are not satisfactory. Also, Hoffmann, who had access to material from only one station, did not address individual variation.

Hoffmann’s description fits well within our description: for instance, the radular formula provided by Hoffmann (120 × 360-0-360) is within the range observed here (85/160 × 150/515-150/515). However, the present study, based on 15 specimens dissected (for 57 specimens examined in total), from nine localities and five of the Galapagos Islands, provides us with the first opportunity to address the character intra-specific variation, which is already given above and is not repeated here. Also, the anatomy of most systems is illustrated here for the first time. Only two nominal species exist in Hoffmannola : H. lesliei and H. hansi . Their differences are discussed under the next species ( H. hansi ).