Geoplana mogi, Ana Laura Almeida & Fernando P. L. Marques & Fernando Carbayo, 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 : 29-32

GEOPLANA MOGI ALMEIDA & CARBAYO SP. NOV.

FIGS 8 AND 9

Geoplana vaginuloides: Marcus, 1951 , p. 54–56.

Material examined

Holotype MZUSP PL 2089 (field number F7000): Parque do Estado, São Paulo / SP, Brazil. O. Françoso and E. M. Froehlich, coll., 29 May 1985. Cephalic region: sagittal sections on ten slides; ovarian region: horizontal sections on 12 slides; pre-pharyngeal region: transverse sections on ten slides; pharynx: sagittal sections on 20 slides; copulatory apparatus: sagittal sections on 35 slides.

Paratype Marcus’ specimen (1951) (from EMF collection): Eldorado neighborhood, West zone of the city of São Paulo/SP, Brazil. E. Marcus and E. M. Froehlich, coll., 1 November 1947. Copulatory apparatus: sagittal sections on five slides.

Paratype MZUSP PL 2061 (field number F1022): Mogi das Cruzes/SP, Brazil (23°27′0 5.5″S, 046°13′40.8″W). F. Carbayo, coll., 27 May 2006. Cephalic region: transverse sections on 13 slides; ovarian region: horizontal sections on seven slides; pre-pharyngeal region: transverse sections on five slides; pharynx: sagittal sections on eight slides; copulatory apparatus: sagittal sections on five slides.

Distribution

Areas covered with secondary Atlantic forest in the municipalities of São Paulo and Mogi das Cruzes, state of São Paulo, Brazil.

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 orangeochre band, bounded on either side by a thin whitish stripe, and in turn this is bordered externally by a thin black line, externally to which is a grey band with dense white mottling, externally to which is a thin marginal black line. Longitudinal parenchymal muscle fibres disposed around intestine as a loose muscular tube. Diameter of muscular cylinder surrounding ejaculatory duct equivalent to 1.3 times the diameter of this duct.

External aspect

Preserved animals 50 mm long and 4 mm wide. Body margins parallel; anterior end rounded, posterior pointed. Dorsum strongly convex, ventral side flat. On histological slides, body 1.25 mm in height. In live animals, dorsal colour pattern constituted by a median orange-ochre band (one-third of body width) that passes into the black of the cephalic region (onefifth of body width), bounded on either side by a thin whitish stripe (one-ninth), and in turn this is bordered externally by a thin black line, externally to which is a grey band (the two latter totalling two-ninths) with dense white mottling, externally to which is a thin marginal black line ( Fig. 8A ). This marginal band was discovered in a detailed examination of the preserved specimen; this band remained hidden in dorsal view owing to the strong convexity of the dorsum. Ventral body surface whitish, with blackish margins. In preserved specimen F1022, whitish, blackish and greyish colours lost brightness; orange-ochre faded. In specimen F7000, median band was ochre-brown bordered on either side by cream lines, in turn this was bordered by a brown green line, externally to which was a beige grey band. Two types of eyes: a conical type, 90 µm high and 40 µm in width; and a cup-shaped type, 40 µm in diameter. The former type contours the anterior tip of the body. Behind the first millimetre, cup-type eyes spread progressively onto the dorsum, reaching the whole dorsum from the pharynx region until posterior end. Sensory pits simple invaginations, 55 μm deep, located ventromarginally in a single row, at least along first third of body from very anterior end. Relative position mouth-tobody length, 55%. Relative position gonopore-to-body length, 71%.

Internal morphology

Creeping sole 78% of body width. Glandular margin absent. Three typical geoplaninid cutaneous muscle layers present, being as thick as 9.5% of body height. Muscle fibres of the longitudinal, innermost layer (40 µm thick) arranged into bundles with 18–20 fibres each. Three parenchymal muscle layers present: dorsal layer of decussate diagonal fibres, supraintestinal layer of transverse fibres, and subintestinal layer with transverse fibres. Longitudinal fibres around intestine present, constituting a loose tube with fibres mixing with transverse ones. Ventral nerve plate present. Mouth situated at a distance from root of the pharynx equivalent to 44–46% of pharyngeal pocket length. Pharynx cylindrical, with dorsal insertion slightly posterior to ventral one ( Fig. 8B ). Oesophagus-topharynx ratio, 15%. Outer pharyngeal musculature consisting of a subepithelial layer (5 µm) of longitudinal muscle, followed by a layer (70 µm) of circular fibres, the innermost of which are intermingled with longitudinal muscle fibres. Inner pharynx musculature consisting of a thin subepithelial layer of longitudinal muscle, followed by a layer (70 µm) of circular fibres and an innermost layer (30 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 length of body; posteriormost follicles near pharynx root. Penis bulb elongated, extending posteriorly from 0.5 mm (specimen MZUSP PL 2061) anterior to penis papilla to the level of the gonopore. The bulb consists 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 female atrium. These fibres apparently cross the nerve plate to anchor on the ventral epidermis. Sperm ducts run dorsally to the ovovitelline ducts. Laterally to penis insertion, sperm ducts bend medially and then penetrate the penis bulb ventrolaterally. Subsequently, the ducts recurve and separately open into the sinuous ejaculatory duct ( Figs 8C , 9A ). The latter traverses the central region of the penis papilla to open at its tip. Sperm present in sperm ducts, also along its course within penis bulb. Sperm ducts lined with a cuboidal, ciliated epithelium and surrounded by a 20-µm-thick layer of circular muscles. Ejaculatory duct lined with columnar, ciliated epithelium; epithelium of extrapenial portion pierced by glands producing weakly erythrophil, fine granules, and being surrounded by 60-µm-thick layer of circular muscle fibres. Epithelium of intrapenial portion of ejaculatory duct richly pierced by glands producing erythrophil granules and surrounded by a 20-µm-thick layer of circular muscles, which constitutes a muscular cylinder possessing a diameter equivalent to 1.3 times the diameter of this duct ( Fig. 9B ).

Penis papilla long and cylindrical along most of its length, with dorsal insertion slightly anterior to the ventral. Total length of papilla equal to ten times its greatest diameter, and occupying male atrium and almost entire female atrium; lined with a cuboidal, non-ciliated epithelium, pierced by two types of gland cells, producing coarse erythrophil granules and fine cyanophil granules, respectively. Erythrophil glands pierce anterior and distal third of penis; necks of cyanophil glands pierce dorsal epithelium of second third, and sometimes also the ventral one, and pack space immediately beneath epithelium so that subepithelial muscle fibres are apart from it ( Fig. 9C ). Subepithelial musculature of penis papilla consisting of dense 80- to 90-µm-thick layer of circular muscle, the fibres of which are decussate distally, followed by a 10- to 20-µm thick layer of longitudinal muscle.

Male atrium not folded, lined with a low, non-ciliated epithelium, pierced by some glands secreting amorphous substance, and underlain by 7-µm-thick layer of circular muscles, followed by a nearly inconspicuous layer of longitudinal fibres.

Ovaries elongated, 1.1 mm in maximal anteroposterior diameter, 0.2 mm in dorsoventral width, and situated at a distance from anterior end equivalent to 22% of body length. Ovovitelline ducts emerge from dorsolateral aspect of ovaries laterally to female atrium, curve medially and join common glandular ovovitelline duct dorsally to this atrium. Common glandular ovovitelline duct as long as a third of female atrium length; it communicates with female genital duct, which is a dorso-anteriorly orientated projection of the posterior region of the female atrium ( Fig. 9A ) and is lined with a 25-µm-tall cuboidal, ciliated epithelium.

Female atrium without folds, posterior portion funnel shaped; as long as 1.5 times that of male atrium; anteriorly lined with a cuboidal epithelium; posteriorly lined with a tall epithelium with stratified appearance and intraepithelial holes. Epithelium pierced by two types of glands, producing erythrophil granules and, less abundantly, xanthophil. Epithelium underlain by 5- to 45-µm-thick layer of circular-to-decussate muscle fibres, followed by some longitudinal fibres, and then a layer (50–150 µm thick) of thicker longitudinal fibres.

Figures

Figure 8. Geoplana mogi sp. nov. A, dorsal view of the live specimen MZUSP PL 2061. B, photomicrograph of a sagittal section of the pharynx of specimen MZUSP PL 2089. C, photomicrograph of a sagittal section of the copulatory apparatus of specimen MZUSP PL 2089.

Figure 9. Geoplana mogi sp. nov. A, diagrammatic representation of the copulatory apparatus of the specimen MZUSP PL 2089 from sagittal sections. B, photomicrograph of the ejaculatory duct and its surrounding musculature of specimen MZUSP PL 2089 in sagittal section. C, photomicrograph of dorsal epithelium of penis papilla and erythrophil glands located immediately beneath epithelium of the unlabelled specimen studied by Marcus (1951) in sagittal section.