Geoplana caraguatatuba, 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 : 38-39

GEOPLANA CARAGUATATUBA ALMEIDA & CARBAYO SP. NOV.

Material examined

All specimens were collected in Parque Estadual Serra do Mar, Caraguatatuba/SP, Brazil.

Holotype MZUSP PL 2091 (field number F7004; 23°35′38.0″S, 045°25′47.1″W): F. Carbayo et al., coll., 14 May 14 2016. Ovarian region: horizontal sections on eight slides; pre-pharyngeal region: transverse sections on seven slides; pharynx and copulatory apparatus: sagittal sections on 34 slides.

Paratype MZUSP PL 2080 (field number F6727; 23°35′38.4″S, 045°25′46.8″W): F. Carbayo et al., coll., 2 July 2015. Before sectioning, copulatory apparatus studied on images of orthogonal virtual sections obtained by µCT. Ovarian region: horizontal sections on eight slides; pre-pharyngeal region: transverse sections on nine slides; pharynx and copulatory apparatus: sagittal sections on eight slides.

Paraype MZUSP PL 2126 (field number F6976; 23°35′38.0″S, 045°25′47.1″W): F. Carbayo et al., coll., 1 January 2016. In absolute ethanol.

Distribution

Only known from borders of Atlantic forest in the municipality of Caraguatatuba, state of São Paulo, Brazil.

Etymology

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

Diagnosis

Dorsal colour pattern constituted by a median orangeochre 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 that merges into a grey band with white mottling, which fades gradually towards its outer margin, while this margin is bordered by a black stripe. Penis bulb extending anteriorly 0.8 mm from penis papilla. Wall of female atrium not folded.

External aspect

Live animals 60 mm long and 4 mm wide when extended. Body margins nearly parallel; anterior end rounded, posterior pointed. Dorsum convex, ventral side slightly convex. Dorsal body surface constituted by a median orange-ochre band (one-quarter of body width) that grades into the black of the cephalic region (one-ninth of body length) and of posterior end, bounded on either side by a black line (one-tenth) that join each other posteriorly, external to which is a white stripe (one-ninth), which join each other at the posterior end, and in turn this is externally bordered by a black stripe (one-ninth) that merges into a grey band (one-ninth) with white mottling and which gradually fades towards its outer margin. This margin is bordered by a black line ( Fig. 14A ). Ventral body surface whitish with black margins. In preserved specimens, dorsal black colour became dark greyish, and grey became cream; whitish remained unchanged. Two types of eyes: a conical type contouring only the anterior end; and a cup-shaped type, spreading dorsally onto the surface external to the white stripes. Sensory pits simple invaginations, 50 μm deep, located ventromarginally in a single row from the very anterior end up to the end of first one-third of body. Relative position mouth-to-body length, 55%. Relative position gonopore-to-body length, 69%.

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 (15 µm thick) arranged into bundles with 20–30 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 rarely lateral to intestine. Ventral nerve plate present.

Mouth situated at a distance from root of the pharynx equivalent to 34–60% of pharyngeal pocket length. Pharynx cylindrical, with dorsal insertion posteriorly placed ( Fig. 14B ). Oesophagus-to-pharynx ratio, 14%. Outer pharyngeal musculature consisting of a subepithelial layer (5 µm) of longitudinal muscle, followed by a layer (55 µm) of circular fibres, intermingled with longitudinal ones at its innermost portion. Inner pharynx musculature consisting of a thin subepithelial layer of longitudinal muscle, followed by a layer (35 µm) of circular fibres and an innermost layer (10 µm) of longitudinal fibres ( Fig. 14C ).

Testes dorsally located between supraintestinal parenchymal muscle layer and intestine; anteriormost testes (at a distance from anterior end equal to 25% of body length) behind ovarian region, posteriormost near root of pharynx. Penis bulb elongated, extending from 0.8 mm anterior to penis papilla to the level of the gonopore region; strongly developed, consisting of tightly packed muscle fibres variously orientated, somewhat more developed dorsally than ventrally. Bulb fibres on the right side run obliquely downwards to embrace ventrally the anterior portion of the female atrium, subsequently anchoring presumably on ventral epidermis. Sperm ducts run dorsolaterally or dorsally to the ovovitelline ducts. Laterally to penis bulb, sperm ducts bend anteriorly and medially, and then ventrolaterally penetrate the bulb. The ducts subsequently join to form the ejaculatory duct, with initial section outside penis papilla, then crossing it centrally to open at its tip ( Fig. 15A ). Sperm ducts lined with a cuboidal, ciliated epithelium and surrounded by a 5- to 25-µm-thick layer of circular muscles. Sperm contained in distal portion of sperm ducts, both along their course outside and inside penis bulb. Ejaculatory duct lined with tall, ciliated epithelium; pierced by numerous gland cells producing erythrophil granules, except in its first millimetre. Ejaculatory duct surrounded by a 25-µm-thick layer of circular muscle fibres constituting a muscular cylinder with a diameter equivalent to 1.7 times the diameter of this duct.

Penis papilla 5 mm long, horizontal and cylindrical along most of its length, with dorsal and ventral insertions at the same transverse plane ( Fig. 15A–C ). Total length of papilla equal to seven times its diameter. Papilla covered with a cuboidal epithelium pierced by gland cells producing erythrophil granules; dorsal epithelium of second third of papilla pierced by glands producing cyanophil granules; space immediately beneath this epithelium packed by necks of these cells ( Fig. 15D, E ). Subepithelial musculature consisting of dense layer of circular muscle, 130 µm thick dorsally, 60 µm thick ventrally, followed by a 20-µm-thick layer of longitudinal muscle.

Male atrium ample, not folded, lined with a low, nonciliated epithelium and underlain by an 8-µm-thick layer of circular muscles, followed by an 8-µm-thick layer of longitudinal fibres. Additional longitudinal muscle fibres around atrium dorsal to gonopore canal.

Ovaries are oval shaped, 450 µm in length in longitudinal axis, and situated at a distance from anterior end equivalent to one-quarter of body length. Ovovitelline ducts emerge from dorsolateral aspect of ovaries. Ovaries run laterally to posterior portion of female atrium, then curve medially to communicate with common glandular ovovitelline duct. The latter duct is as long as one-seventh of female atrium length and opens into the female genital duct, a projection of the dorsoposterior region of the female atrium.

Female atrium without folds, cylindrical along most of its course, funnel shaped posteriorly; as long as 1.5 times that of male atrium ( Fig. 15A ); funnelshaped portion lined with tall (20–25 µm) epithelium with stratified aspect, being pierced by two types of glands, producing erythrophil and xanthophil amorphous substance, respectively; cylindrical portion lined with cuboidal epithelium. Female atrium surrounded by 10- to 35-µm-thick layer of circular-to-decussate muscle fibres, followed by a 10- to 65-µm-thick layer of longitudinal fibres.

Figures

Figure 14. Geoplana caraguatatuba Almeida & Carbayo sp. nov. A, dorsal view of the living specimen MZUSP PL 2080, ~42 mm in length. B, photomicrograph of a sagittal section of the pharynx of specimen MZUSP PL 2080. C, photomicrograph of the three muscle layers of the internal musculature pharynx in sagittal section of specimen MZUSP PL 2080.

Figure 15. Geoplana caraguatatuba Almeida & Carbayo sp. nov. Specimen MZUSP PL 2080. A, diagrammatic representation of the copulatory apparatus from sagittal sections. B, photomicrograph of a sagittal section of the copulatory apparatus. C, virtual sagittal section of the copulatory apparatus derived from the micro-computed tomography dataset. D, virtual transverse section derived from the micro-computed tomography dataset of the body at the level of the gonopore. E, photomicrograph of dorsal epithelium of penis papilla and cyanophil glands located immediately beneath epithelium in sagittal section.