Geoplana cananeia, 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 : 43-45

GEOPLANA CANANEIA ALMEIDA & CARBAYO SP. NOV.

FIG. 17

Material examined

All specimens were collected in Parque Estadual da Ilha do Cardoso, Cananeia / SP, Brazil (25°05′28.4″S, 047°55′44.2″W). J. Pedroni, coll., 18 October 2009.

Holotype MZUSP PL 2067 (field number F4096): Cephalic region: horizontal sections on five slides; ovarian region: horizontal sections on 12 slides; prepharyngeal region: transverse section on 12 slides; pharynx: sagittal sections on 17 slides; copulatory apparatus: sagittal sections on 45 slides.

Paratype MZUSP PL 2068 (field number F4097): pharynx: transverse sections on six slides; undeveloped copulatory apparatus: sagittal sections on three slides.

Paratype MZUSP PL 2069 (field number F4098): pharynx: sagittal sections on eight slides; copulatory apparatus: sagittal sections on 13 slides.

Distribution

Area covered with Atlantic forest in Cardoso Island, municipality of Cananeia, state of São Paulo.

Etymology

The specific epithet refers to the Tupi-Guarani (indigenous Brazilian tribe) name of the municipality where the species was collected.

Diagnosis

Dorsal colour pattern constituted by a median yellow orange band, bounded on either side by a black stripe, externally to which is a white stripe, and this in turn is externally bordered by a black stripe, which merges into a grey band with white mottling, which gradually fades towards its outer margin, while this margin is bordered by a thin black stripe. Penis bulb extending anteriorly 1 mm from penis papilla. Stroma of the penis papilla with necks of glands gathered in bundles resembling an orange in cross-section. Wall of posterior half of female atrium richly folded.

External aspect

Adults up to 66 mm long and 5 mm wide. Body margins nearly parallel; anterior end rounded, posterior pointed. Dorsum strongly convex, ventral side flat. Dorsal body surface constituted by a median yellow-orange band (approximately one-quarter of body width) that grades into the black of cephalic region (1/13th of body length), bounded on either side by a black stripe (one-sixth) which join posteriorly, externally to wh ich is a white stripe (one-seventh), and this in turn is bordered externally by a black stripe, which merges into a grey band with white mottling (one-sixth), which gradually fades towards its outer margin, while this margin is bordered by a thin black stripe ( Fig. 17A ). Ventral surface is whitish with black margins. The dorsal colours of preserved specimens remained unchanged. Two types of eyes: a conical type, in a single row around anterior tip; and a cup-shaped type, spreading onto dorsum, reaching whitish stripes except at the anterior extremity of the body. Sensory pits simple invaginations, 20 μm deep, located ventromarginally in a single row, from the very anterior end up to at least first one-sixth of body length. Relative position mouth-to-body length, 55%. Relative position gonopore-to-body length, 70%.

Internal morphology

Creeping sole 84% of body width. Glandular margin absent. Three typical geoplaninid cutaneous muscle layers present, being as thick as 5–6% of body height. Muscle fibres of the longitudinal, innermost layer (25 µm thick) arranged into bundles with 25–33 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 are 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 29% of pharyngeal pocket length. Pharynx cylindrical, with dorsal insertion slightly posterior to ventral one ( Fig. 17B ). Oesophagus- to-pharynx ratio, 12%. Outer pharyngeal musculature consisting of a subepithelial layer (5 µm) of longitudinal muscle, followed by a layer (50 µm) of circular muscle fibres with longitudinal ones in its innermost region. 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 slightly behind ovarian region (equivalent to 20% of body length), posteriormost follicles slightly anterior to the root of the pharynx. Penis bulb elongated, extending from 1 mm anterior to penis papilla to the level of the gonopore region; well developed, consisting of tightly packed muscle fibres variously orientated. Diagonal fibres on the right side of the bulb run obliquely downwards to embrace ventrally the anterior portion of the female atrium. These fibres apparently mix with the subintestinal parenchymal musculature. 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 recurve, then join to form the ejaculatory duct. This wide canal ( Fig. 17C ) initially curves dorsoposteriorly, then enters penis papilla and traverses it sinuously to open at its distal tip. Sperm present in distal portion of sperm ducts, along their course both outside and inside penis bulb. Ejaculatory duct lined with columnar, ciliated epithelium, 25–40 µm high in anterior portion, 40–50 µm high inside the papilla, and surrounded by a 40-µm-thick layer of circular muscle fibres, which constitutes a muscular cylinder with a diamter equivalent to 1.5 times the diameter of this duct. Extrapapillar and anterior portion of ejaculatory duct pierced by numerous gland cells producing fine erythrophil granules; from that portion until nearly the tip of papilla the duct is pierced by cells producing coarse erythrophil granules.

Penis papilla long, horizontal and cylindrical, with dorsal insertion slightly anterior to the ventral part; tip blunt. The papilla occupies the male atrium and anterior two-fifths of the female atrium. Total length of papilla equal to six times its greatest diameter. It is covered with a squamous epithelium, which is pierced by two types of very abundant gland cells, producing fine erythrophil and cyanophil granules, respectively, with the former being more abundant. Necks of these two types of glands progressively gather in larger and less numerous bundles; in the distal portion of the papilla, erythrophil necks are gathered in nine to 14 bundles, which are separated from each other by cyanophil glands, thus giving rise to a picture resembling an orange in cross-section ( Fig. 17D, E ). Subepithelial musculature consisting of dense 50-µm-thick layer of circular muscle, slightly decussate, followed by a 20-µm-thick layer of longitudinal muscle.

Male atrium ample, not folded ( Fig. 17E ), lined with a squamous epithelium pierced by glands secreting an amorphous erythrophil substance, and underlain by a 5-µm-thick layer of circular muscles, followed by a thin layer of longitudinal fibres. Circular muscle fibres surround both innermost portions of gonopore canal and nearby atrium.

Ovaries oval shaped, 500 µm in length in the longitudinal 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 hind region of female atrium, the ducts curve medially and join to form common glandular ovovitelline duct. This duct is as long as one-sixth of female atrium length; it first bends posteroventrally, then curves anteriorly to open into female genital duct; the latter is a projection of the posterior region of the female atrium and lined with a 12-µm-high columnar, ciliated epithelium.

Female atrium long, twice as long as male atrium ( Fig. 17E ); anterior half spacious and lined with cuboidal epithelium; hind half has richly folded wall projected into its own lumen consisting of 25-µm-high, stratified-like epithelium. Two types of gland pierce female epithelium, producing erythrophil and cyanophil granules, respectively, the second being more abundant in posterior half. Atrium surrounded by 25- to 40-µm-thick subepithelial layer of circular muscle fibres, followed by a layer of longitudinal fibres, partly interwoven with the circular ones.

Figures

Figure 17. Geoplana cananeia Almeida & Carbayo sp. nov. Specimen MZUSP PL 2067. A, dorsal view of the living specimen, ~65 mm in length. B, photomicrograph of a sagittal section of the pharynx. C, photomicrograph of a transverse section of ejaculatory duct. D, photomicrograph of an oblique section of the distal portion of the penis papilla; note the gland necks gathered into dense bundles. E, diagrammatic representation of the copulatory apparatus from sagittal sections.