Geoplana boraceia, 2019

Ana Laura Almeida, Fernando P. L. Marques & Fernando Carbayo, 2019, ‘ Endless forms most beautiful’: taxonomic revision of the planarian Geoplana vaginuloides (Darwin, 1844) and discovery of numerous congeners (Platyhelminthes: Tricladida), Zoological Journal of the Linnean Society 185, pp. 1-65 : 56-60

GEOPLANA BORACEIA ALMEIDA & CARBAYO SP. NOV.

FIGS 25 AND 26

Material examined

Holotype MZUSP PL 2070 (field number F4112): Estação Biológica de Boraceia, Salesópolis / SP, Brazil (23°39′14.0″S, 045°53′21.0″W). F. Carbayo et al., coll., 21 December 2009. Cephalic region: horizontal sections on 11 slides; ovarian region: horizontal sections on four slides; pre-pharyngeal region: transverse sections on eight slides; pharynx: sagittal sections on six slides; copulatory apparatus: sagittal sections on 12 slides.

Paratype MZUSP PL 2077 (field number F6575): São Sebastião/SP, Brazil (23°44′48.7″S, 045°37′55.7″W). A. L. Almeida et al., coll., 13 February 2015. Ovarian region: horizontal sections on seven slides; pre-pharyngeal region: transverse sections on ten slides; pharynx and copulatory apparatus: sagittal sections on 15 slides.

Paratype MZUSP PL 2078 (field number F6578): São Sebastião/SP, Brazil (23°44′48.7″S, 045°37′55.7″W). A. L. Almeida et al., coll., 13 February 2015. Ovarian region: horizontal sections on seven slides; prepharyngeal region: transverse sections on ten slides; pharynx and copulatory apparatus: sagittal sections on nine slides.

Paratype MZUSP PL 2073 (field number F6357): São Sebastião/SP, Brazil (23°44′48.7″S, 045°37′55.7″W). A. L. Almeida et al., coll., 29 April 2015. Copulatory apparatus: sagittal sections on 11 slides.

Paratype MZUSP PL 2123 (field number F4389): São Sebastião/SP, Brazil (23°44′45.6″S, 045°37′55.2″W). F. Carbayo et al., coll., 26 February 2010. Entire specimen in 80% ethanol.

Paratype MZUSP PL 2095 (field number F6026): São Sebastião/SP, Brazil (23°44′39.8″S, 045°38′13.7″W). Carbayo et al., coll., 11 January 2014. Preserved in 80% ethanol.

Paratype MZUSP PL 2085 (field number F6994): Estação Biológica de Boraceia, Salesópolis/SP, Brazil. O. Froehlich et al., coll., 14 September 1986. Pharynx and copulatory apparatus: sagittal sections on 48 slides.

Paratype MZUSP PL 2124 (field number F6068): São Sebastião/SP, Brazil (23°44′48.7″S, 045°37′55.7″W). Carbayo et al., coll., 12 January 2014. Preserved in 100% ethanol.

Paratype MZUSP PL 2125 (field number F6055): São Sebastião/SP, Brazil (23°44′24″S 45°37′48″W). Carbayo et al., coll., 11 January 2014. Preserved in 80% ethanol.

Paratype MZUSP PL 1086 (field number F4358): São Sebastião/SP, Brazil (23°45′0 7.3″S, 045°37′51.7″W). Carbayo et al., coll., 26 February 2010. Pre-pharyngeal region: transverse sections on five slides; pharynx: sagittal sections on 12 slides; copulatory apparatus: sagittal sections on 12 slides.

Distribution

Areas covered with Atlantic forest in the municipalities of Salesópolis and São Sebastião, state of São Paulo, Brazil.

Diagnosis

Dorsal colour pattern constituted by a median mustard-coloured band, bounded on either side by a black band; entire dorsum sprinkled with conspicuous whitish specks. Penis bulb extending anteriorly 0.8 mm from penis papilla. Diameter of muscular cylinder around ejaculatory duct equivalent to 1.5 times the diameter of this duct. Female-to-male atrial length ratio, ~1.0.

Etymology

The specific epithet refers to the name of the biological station where the type material was collected.

External aspect

Preserved adults 50 mm long and 4 mm wide. Body elongated, margins nearly parallel; anterior end rounded, posterior pointed. Dorsum strongly convex, ventral side flat. Dorsal body surface constituted by a median mustard-coloured band (one-third of body width) that grades into the black of cephalic region (one-sixth of body length), bounded on either side by a black band (one-third); entire dorsum sprinkled with conspicuous whitish specks ( Fig. 25A ). Ventral surface is grey whitish, with blackish margins. In fixed specimens, dorsal colours faded, mostly the median band. Two types of eyes: a conical type, in a single row around anterior tip; and a cup-shaped type, spreading onto dorsum along lateral bands with one-third of body width. Sensory pits simple invaginations, 40 µm deep, located ventromarginally in a single row, from the very anterior end up to at least the first one-eighth of body length. Relative position mouth-to-body length, 57%. Relative position gonopore-to-body length, 70%.

Internal morphology

Creeping sole 85% of body width. Glandular margin absent. Three typical geoplaninid cutaneous muscle layers present, as thick as 9% of body height. Muscle fibres of the longitudinal, innermost layer (20–25 µm thick) arranged into bundles with nine to 30 fibres each. Three parenchymal muscle layers present: dorsal layer of decussate diagonal fibres, supraintestinal layer of transverse and longitudinal fibres, and subintestinal layer with transverse and longitudinal fibres. Longitudinal fibres around intestine present, constituting a loose tube whose fibres mix with transverse ones. Ventral nerve plate present.

Mouth situated at a distance from root of the pharynx equivalent to 34–49% of pharyngeal pocket length. Pharynx cylindrical, dorsal insertion slightly posterior. Oesophagus-to-pharynx ratio, 10% ( Fig. 25B ). Outer pharyngeal musculature consisting of a subepithelial layer (2.5 µm) of longitudinal muscle, followed by a layer (35 µm) of circular fibres, the innermost of which are intermingled with longitudinal ones. Inner pharynx musculature consisting of a thin subepithelial layer of longitudinal muscle, followed by a layer (50 µm) of circular fibres and an innermost layer (15 µm) of longitudinal fibres.

Testes dorsally located between supraintestinal parenchymal muscle layer and intestine; anteriormost testes at a distance from anterior end equivalent to 22% of body length; posteriormost testes slightly anterior to root of pharynx. Penis bulb elongated, extending from 0.8 mm anterior to penis papilla to the level of gonopore region; well developed, dorsally more than ventrally. It consists of tightly packed muscle fibres variously orientated proximally. Part of the muscle fibres from the right dorsal portion of penis bulb detach and, subsequently, run obliquely downwards to embrace ventro-anterior portion of the female atrium ( Fig. 25D, E ). Further course of these fibres could not be determined. A lower number of muscle fibres from the dorsoposterior left portion of penis bulb run anteroventrally towards ventral epidermis; further course of these fibres could not be determined.

Sperm ducts run dorsolaterally or dorso-internally to the ovovitelline ducts. Laterally to level of the insertion of penis papilla, the sperm ducts bend medially and then ventrolaterally to penetrate the bulb. The ducts subsequently recurve and join to continue posteriorly as an unpaired, curved duct; the unpaired portion continues as the ejaculatory duct. The latter follows a sinuous course to open at the tip of the penis papilla ( Figs 25C, D , 26A, B ). Sperm present in distal portion of sperm ducts, along both their course outside and inside penis bulb. Sperm ducts lined with a cuboidal-to-columnar, ciliated epithelium and surrounded by a 12-µm-thick layer of circular muscles. Ejaculatory duct lined with tall, ciliated epithelium; extrapapillar section pierced by gland cells producing fine, weakly cyanophil granules, but this cell type may extend along intrapapillar section until the level of the gonopore; intrapapillar section pierced by conspicuous and numerous gland cells producing erythrophil-to-xanthophil granules; surrounded by a 10-µm-thick layer of circular muscles, and constituting a muscular cylinder with a diameter equivalent of 1.5 times the diameter of this duct.

Penis papilla long, horizontal and cylindrical along most of its length; distally conical. Dorsal and ventral insertions of this papilla approximately at the same transverse plane. This papilla occupies the entire male atrium and the first half of the female atrium. Total length of papilla equal to six to seven times its greatest diameter. Penis papilla covered with a squamousto-cuboidal epithelium, pierced by two types of gland cells, producing strongly erythrophil granules and fine cyanophil granules, respectively; former glands pierce entire epithelium except for mid-dorsal; this area pierced by cyanophil glands, the necks of which pack the space immediately beneath this epithelium ( Fig. 25C ). Subepithelial musculature consisting of a dense layer of circular muscle, decussates distally, 110 µm thick dorsally, 55 µm ventrally, followed by a 15-µm-thick layer of longitudinal muscle. Male atrium ample, not folded, and lined with a low, non-ciliated epithelium, pierced by gland cells producing erythrophil granules and underlain by a 10-µm-thick layer of circular muscles, followed by a 10-µm-thick layer of longitudinal fibres.

Ovaries oval shaped, 500 µm in diameter in anterior–posterior axis, and situated at a distance from anterior end equivalent to one-fifth of body length. Ovovitelline ducts emerge from dorsolateral wall of ovaries. Laterally to female atrium, the oviducts curve medially and join to form the common glandular ovovitelline duct. This duct is as long as 20–30% of female atrium length and communicates with female genital duct; the latter is a canalicular projection of the posterior region of the female atrium, and is lined with a 25-µm-tall stratified-like, ciliated epithelium.

Female atrium cylindrical, becoming conical posteriorly, sometimes here with small folds ( Figs 25C , 26A, D ); a little longer than the male atrium. Conical portion lined with a stratified-like epithelium; cylindrical portion lined with cuboidal epithelium; both epithelia pierced by two types of gland cells, producing amorphous substance; surrounded by 5- to 20-µm-thick layer of circular-to-decussate muscle fibres, followed by a layer of longitudinal fibres, 125 µm thick in posterior portion, 20 µm in anterior portion.

Figures

Figure 25. Geoplana boraceia Almeida & Carbayo sp. nov. A, dorsal view of the living specimen MZUSP PL 1086 (field number F4358), ~40 mm in length. B, photomicrograph of a sagittal section of the pharynx of specimen MZUSP PL 2077. C, photomicrograph of a sagittal section of penis papilla and female atrium of specimen MZUSP PL 2070. D, micro-computed tomography-based image of a transverse section of the penis papilla of specimen MZUSP PL 2095. Arrows point to muscle detached from the penis bulb running towards the ventral epidermis. Right body side to the right. E, micro-computed tomography-based image of a parasagittal section of the right side of penis bulb of specimen MZUSP PL 2095. Arrows point to muscles detached from the penis bulb running towards the ventral epidermis.

Figure 26. Geoplana boraceia Almeida & Carbayo sp. nov. Sagittal views. A, diagrammatic representation of the copulatory apparatus of specimen MZUSP PL 2070. B, photomicrograph of a sagittal section of the penis bulb of specimen MZUSP PL 2070. C, photomicrograph of dorsal epithelium of penis papilla and cyanophil glands located immediately beneath epithelium of specimen MZUSP PL 2077. D, photomicrograph of posterior portion of female atrium and female genital duct of specimen MZUSP PL 2070.