Geoplana cambara, 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 : 46-48

GEOPLANA CAMBARA ALMEIDA & CARBAYO SP. NOV.

Material examined

All specimens were collected in Parque Nacional de Saint-Hilaire/Lange, Matinhos/PR, Brazil.

Holotype MZUSP PL 2062 (field number F1611): F. Carbayo et al., coll., 10 January 2008. Cephalic region: transverse sections on 21 slides; ovarian region: horizontal sections on 13 slides; pharynx: transverse sections on 18 slides; copulatory apparatus: sagittal sections on 15 slides.

Paratype MZUSP PL 2063 (field number F1635) (immature): F. Carbayo et al., coll., 11 January 2008. Cephalic region: horizontal sections on nine slides; pharynx: sagittal sections on five slides; portion behind pharynx: sagittal sections on four slides.

Paratype MZUSP PL 1009 (field number F1614): F. Carbayo et al., coll., 1 January 2008 (25°45′51.7″S, 048°37′21.6″W). Preserved in absolute ethanol.

Distribution

Areas covered with Atlantic forest in Parque Nacional de Saint-Hilaire/Lange, Matinhos, state of Paraná, Brazil.

Etymology

The specific epithet refers to the Tupi-Guarani (indigenous Brazilian tribe) name of the river flowing nearby the sampling site.

Diagnosis

Dorsal colour pattern constituted by a median orange stripe, bounded on either side by a thin black stripe, externally to which is a broader white stripe, and this in turn is externally bordered by a black line, externally to which is a grey band with dense white mottling, externally to which is a marginal black line. Longitudinal parenchymal muscle fibres disposed around intestine as a loose muscular tube. Diameter of muscular cylinder surrounding ejaculatory duct equivalent to 12 times the diameter of this duct.

External aspect

Live animals 43 mm long and 3.5 mm wide. Body elongated, margins nearly parallel; anterior end rounded, posterior pointed. Dorsum strongly convex, ventral side flat. Dorsal colour constituted by a median orange band, bounded on either side by a thin black stripe (one-third of body width) that grades into the black of the cephalic region (1/12th of body length), externally to which is a broader white stripe (one-sixth), and this in turn is externally bordered by a black line, externally to which is an area (one-sixth) coloured with a grey band with dense white mottling, externally to which is a marginal black line ( Fig. 18A ). Ventral body surface cream, with black margins. The dorsal colours of preserved specimens remained unchanged. Two types of eyes: a conical type, around anterior tip; and a cup-shaped type, which are located from a short distance behind anterior tip to posterior end, extending dorsally onto whitish stripes. Sensory pits simple invaginations, located ventromarginally in a single row from the very anterior end up to at least a distance equivalent to 13% of body length. Relative position mouth-to-body length, 50%. Relative position gonopore-to-body length, 64%.

Internal morphology

Creeping sole 80% of body width. Glandular margin absent. Three typical geoplaninid cutaneous muscle layers present, being as thick as 6% of body height. Muscle fibres of the longitudinal, innermost layer (6–12 µm thick) arranged into bundles with seven to 20 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 of fibres mixed up with transverse ones. Ventral nerve plate present.

Mouth situated at a distance from root of the pharynx equivalent to 47% of pharyngeal pocket length. Pharynx cylindrical ( Fig. 18B ). Oesophagus-topharynx ratio, 17%. Outer pharyngeal musculature consisting of a subepithelial layer (5 µm) of longitudinal muscle, followed by a layer (65 µm) of intermingled circular and longitudinal muscle fibres. Inner pharynx musculature ( Fig. 18C ) consisting of a thin subepithelial layer of longitudinal muscle, followed by a layer (45 µm) of circular fibres and an innermost layer (10 µm) of longitudinal fibres.

Testes dorsally located between supraintestinal parenchymal muscle layer and intestine; anteriormost testes slightly anterior to ovarian region, posteriormost follicles slightly anterior to root of pharynx. Penis bulb elongated, extending from 1.2 mm anterior to penis papilla to behind level of gonopore; very strongly developed dorsally to male atrium. It consists of tightly packed muscle fibres variously orientated anteriorly. Diagonal fibres on the right side of the bulb run obliquely downwards to embrace ventrally the anterior portion of the female atrium. Those fibres seem to cross the nerve plate and to anchor on ventral epidermis. Sperm ducts run dorsolaterally to the ovovitelline ducts. Laterally to ventral insertion of penis papilla, sperm ducts bend anteriorly and medially and then ventrolaterally to penetrate the bulb. The ducts subsequently join near root of penis papilla to form the ejaculatory duct. This duct traverses the central region of penis papilla to open at its tip ( Fig. 18D, E ). Sperm present in distal portion of sperm ducts, along their course both outside and inside penis bulb. Sperm ducts lined with a cuboidal, ciliated epithelium, pierced by glands producing fine weakly erythrophil granules; sperm ducts and anterior portion of ejaculatory duct surrounded by a circular muscle. Distal portion of ejaculatory duct surrounded by a layer of circular-to-decussate muscles. Thickness of muscles surrounding the ejaculatory duct increases from 50 µm proximally to a maximum of 150 µm in mid-papilla, and constituting a muscular cylinder with a diameter equivalent to 12 times the diameter of this duct.

Penis papilla long, horizontal and cylindrical, with dorsal and ventral insertions at the same transverse plane; tip pointed ( Fig. 18D, E ). It occupies the entire male atrium and most of the female atrium. Total length of papilla equal to seven times its greatest diameter. Papilla covered with a cuboidal epithelium, pierced by two types of gland cells, producing erythrophil and cyanophil granules, respectively. Space immediately beneath mid-dorsal epithelium of papilla packed by necks of latter type of gland cells ( Fig. 19A, B ). Subepithelial musculature consisting of dense layer of circular muscle, tending to decussate distally, 185 µm thick dorsally, 145 µm ventrally, followed by a 15-µm-thick layer of longitudinal muscle. Distally, abundant decussate fibres in stroma. Male atrium ample, not folded, lined with a squamous epithelium, and underlain by a 5-µm-thick layer of circular muscles, followed by an inconspicuous layer of longitudinal fibres.

Ovaries oval shaped, 425 µm in diameter in longitudinal axis, and situated at a distance from anterior end equivalent to 17% of body length. Ovovitelline ducts emerge from dorsolateral wall of ovaries. Laterally to female atrium, the oviducts curve medially and join to form common glandular ovovitelline duct. Common glandular ovovitelline duct as long as a quarter of female atrium length, after a knee-shaped bend communicating with a 30-µm-long female genital duct lined with cuboidal, ciliated epithelium, the latter opening into the female atrium.

Female atrium long, not folded ( Figs 18D , 19C, D ) and as long as two times the male atrium. Posterior, curved section lined with 20-µm-tall stratified-like, non-ciliated epithelium and surrounded by a 30-µmthick mass of very thin, seemingly circular muscle fibres, mixed with apparently minute erythrophil granules ( Fig. 19D ). Anterior section of female atrium lined with cuboidal epithelium and surrounded by a 10- to 40-µm-thick layer of circular and longitudinal muscle fibres. A 10- to 110-µm-thick layer of longitudinal muscles embraces entire female atrium.

Figures

Figure 18. Geoplana cambara Almeida & Carbayo sp. nov. A, dorsal view of the living specimen MZUSP PL 2062, ~43 mm in length. B, photomicrograph of a sagittal section of the pharynx of specimen MZUSP PL 2063. C, photomicrograph of a sagittal section of the inner pharyngeal epithelium showing its two muscle layers (each indicated with an arrowhead) of specimen MZUSP PL 2063. D, photomicrograph of a sagittal section of the copulatory apparatus of specimen MZUSP PL 2062. D, diagrammatic representation of the copulatory apparatus of specimen MZUSP PL 2062.

Figure 19. Geoplana cambara Almeida & Carbayo sp. nov. Photomicrographs of sagittal sections of specimen MZUSP PL 2062. A, mid-portion of penis papilla, with the ejaculatory duct and its surrounding muscle. B, dorsal epithelium of penis papilla and cyanophil glands located immediately beneath epithelium. C, female atrium. D, female genital duct; note layer of very thin muscle fibres surrounding the duct.