Choeradoplana banga, Carbayo & Froehlich, 2012

Carbayo, Fernando & Froehlich, Eudóxia Maria, 2012, Three new Brazilian species of the land planarian Choeradoplana (Platyhelminthes: Tricladida: Geoplaninae), and an emendation of the genus, Journal of Natural History 46 (19 - 20), pp. 1153-1177 : 1162-1168

Choeradoplana banga sp. nov.

( Figures 9–15 ; Tables 3, 4)

Type material

Holotype. MZUSP PL 1000 : Parque Estadual da Serra da Cantareira , São Paulo / SP, Brazil, c. 23 ◦ 25 ′ 45 ′′ S, 46 ◦ 37 ′ 57 ′′ W, F. Carbayo et al. col., 30 January 2008. Cephalic region: sagittal sections on six slides; anterior region 2: sagittal sections on 12 slides; anterior region 3: horizontal sections on five slides; pre-pharyngeal region: transverse sections on five slides; pharynx and copulatory apparatus: sagittal sections on 15 slides.

Paratypes. MZUSP PL 1001 : ibid., 23 ◦ 25 ′ 44.9" S, 46 ◦ 37 ′ 57 ′′ W, F. Carbayo et al., col., 14 December 2008. Pharynx : sagittal sections on 21 slides; copulatory apparatus: sagittal sections on 17 slides ; MZUSP PL 1002 . ibid., 23 ◦ 25 ′ 44.9" S, 46 ◦ 37 ′ 57 ′′ W, F. Carbayo et al., col., 14 December 2008. Cephalic region : sagital sections on six slides; anterior region 2: sagittal sections on eight slides; pre-pharyngeal region: transverse sections on three slides; pharynx: sagittal sections on 10 slides; copulatory apparatus: sagittal sections on 18 slides .

Type locality

Parque Estadual da Serra da Cantareira, São Paulo / SP, Brazil, covered with secondary Atlantic Rainforest.

Etymology

In Tupi-Guarani language banga means bent or reverse; it alludes to the ventral, behind the atrium, approach of the common glandular ovovitelline duct, in contrast to what has been described for the genus.

Diagnosis

Choeradoplana with pale ochre dorsum, with numerous brown-to-black irregular small spots arranged in a network design; pharynx bell-shaped; prostatic vesicle intrabulbar; narrow female atrium; common glandular ovovitelline duct approaching the vagina behind the atrium, from the ventral side; a massive sphincter ventral to male and female atria, adjacent to the gonopore canal.

Description

Paratype MZUSP PL 1002 , the largest specimen when alive, measured up to 45 mm in length and 2 mm in width. After fixation paratype measured 44 mm in length and

G, gonopore; L, length; M, mouth; W, width.

3 mm in width ( Table 3). Body elongated, with anterior end slightly dilated, provided with the two glandular cushions ventrally separated by a longitudinal groove, diagnostic of the genus ( Figure 9 ). As characteristic for the genus, live worms held the anterior extremity dorso-posteriorly rolled. Posterior end pointed. Dorsum highly convex in cross-section; body margins rounded; ventral side slightly convex. Dorsal background colour pale ochre, with numerous small irregular dark brown spots, most confluent, creating a network design. Body margins slightly ferruginous; ventral side pale yellowish. Mouth 20 mm and gonopore at 28.5 mm from anterior end (holotype).

Eyes formed by one pigmented cup c.55 µm in diameter, absent in the first 0.25 mm. From this point on, distributed marginally in an irregular row of two or three eyes, up to posterior end of body. Sensory pits 35 µm deep, located ventro-marginally, from 2 mm to 8.2 mm behind anterior end (paratype MZUSP PL 1001).

Epidermis ciliated only over creeping sole. Rhabditogen cells open onto whole cephalic surface, more densely through epithelium of glandular cushions. Cellular bodies of cephalic cushion erythrophil glands located between longitudinal cutaneous muscle layer and epithelium.

At anterior end, 2.2 mm behind apex, ventral nerve plate (100 µm thick) gives rise to an ill-defined cerebral ganglion (approximately 200 µm thick and 2 mm long) (holotype).

Cutaneous musculature comprising three typical layers of Geoplaninae species, namely, a subepithelial more external layer of circular fibres, and then a double layer of diagonal decussated fibres, and then one of longitudinal fibres, arranged into dense bundles ( Figure 10 ; Table 4). Ventrally, layer of longitudinal fibres partially sunk into the parenchyma and with its fibres seemingly not joined into bundles. CMI 29.5%. In cephalic region sunken cutaneous longitudinal muscle fibres gather medianly forming retractor, unroller of whole extremity, as described by Froehlich (1955) for C. iheringi .

Three parenchymal muscle layers: a dorsal weak layer of diagonal, decussated fibres (30–35 µm thick, holotype), located immediately under the dorsal subcutaneous nerve net, and two transverse layers, one supraintestinal (80–105 µm thick) and other subintestinal (75 µm thick) ( Figure 10 ). In cephalic region there is an additional layer (20 µm thick) of transverse muscle fibres, located under ventral nerve plate.

Mouth in middle of pharyngeal pouch ( Figure 11 ), 20 mm from anterior body end (holotype). Pharyngeal pouch lined with non-ciliated, cubic-to-flat epithelium, underlain by a one-fibre thick layer of circular muscle fibres. Pharynx bell-shaped, tending to collar-shape. Outer pharyngeal epithelium flat, ciliated, underlain by onefibre thick longitudinal muscle layer, then by a layer of circular fibres (15 µm thick) with interspersed longitudinal fibres. Inner pharyngeal epithelium cuboidal, ciliated, underlain by a circular muscle layer (50 µm thick) with interspersed longitudinal fibres.

Testes located between supraintestinal muscle layer and intestine. Distributed on each side of the body in a single-to-triple row from ovarian level (6.6 mm from anterior end) to dorsal pharyngeal insertion, at 23 mm from anterior end (holotype). Anteriormost testes 2.5 mm behind cerebral ganglia. Sperm ducts running immediately above subintestinal muscle layer, dorsal to ovovitelline ducts. Close to copulatory apparatus they curve anterodorsally and medianly, before penetrating the penial bulb to open at each side of proximal tubular portion of prostatic vesicle ( Figures 12–15 ). Distally, vesicle widens acquiring an irregular shape and very folded walls. It communicates amply with male cavity, without an ejaculatory duct. Entally, male atrium is spacious with several small folds, especially from dorsal wall; ectally, mainly because of a bulky fold from the ventral wall, it becomes a long narrow canal.

Epithelium of tubular portion of prostatic vesicle columnar, ciliated, crossed by cell glands with fine erythrophil granules; dilated portion lined with columnar, irregularly ciliated epithelium. Pierced by cell glands containing gross erythrophil granules, and underlain by a 15-µm-thick circular muscle layer. In holotype, tubular portion of prostatic vesicle contains sperm.

Male atrium clothed proximally with a columnar epithelium that becomes cubic distally; irregularly ciliated all along. It is crossed by secretory cells of two types, containing erythrophil and cyanophil granular secretions, respectively. Its muscularis is an 8-µm-thick layer of circular fibres. Between common muscular coat and muscularis is a dense mass of muscle fibres without clear orientation. In paratype MZUSP PL 1001 , male atrial cavity is partially filled by an ejaculate with sperm and erythrophil secretion .

Ovaries globular, approximately 320 µm in diameter, located 2.5 mm behind cerebral ganglia, immediately above ventral nerve plate (holotype). Ovovitelline ducts arise from external side of ovaries, and run backwards between muscle fibres of subintestinal transverse muscle layer. They proceed inclined medianly and slightly to the dorsum passing female atrium. Behind female atrium at half the height of dorsum, they curve upwards, and unite with short common glandular ovovitelline duct. The latter joins the vagina, a posteriorly directed tubular diverticle of female atrium. Female atrium is a narrow cavity, as long as one-quarter of male atrium.

Female atrium and vagina, both lined with columnar non-ciliated epithelium, crossed by two types of glands, respectively, erythrophil and cyanophil. Female atrium with 6-µm-thick coat of interwoven muscle fibres; vagina with thin coat of circular fibres.

Ventrally, in the wall of male and female atrium adjacent to gonopore canal, is an extraordinarily massive muscular sphincter, 500 µm thick, composed of circular fibres interspersed with very scarce longitudinal fibres. Gonopore canal lined with columnar, ciliated epithelium underlain by 20-µm-thick circular musculature.

Common muscular coat consists of a dense layer, 80–120 µm thick, of interwoven fibres embracing the whole copulatory complex.

Discussion

Externally, C. banga is hardly distinguishable from C. iheringi , to such an extent that, convinced that we were dealing with a C. iheringi specimen, we removed and degraded a piece of the paratype MZUSP PL1001 for DNA extraction without having previously measured the worm’s length. Specimens of C. iheringi have been collected in Teresópolis, RJ ( Riester 1938), Ribeirão Pires, SP ( Marcus 1951) and Salesópolis, SP ( Leal-Zanchet and Souza 2003). Ribeirão Pires is the closest to the type locality of C. banga , approximately 40 km away.

Regarding the anatomy, the copulatory complex of C. banga possesses two important peculiarities. One is the female genital canal (vagina plus common glandular ovovitelline duct) flexing downwards to receive both ovovitelline ducts that finish their ascending path behind the copulatory complex, before attaining the dorsum. This is a unique arrangement of the female genital ducts (female genital canal plus ovovitelline ducts) previously not described in Choeradoplana . All the previously described species, C. iheringi included, as remarked by Ogren and Kawakatsu (1990), have the female genital canal dorsally or dorso-anteriorly flexed, and the ovovitelline ducts ascending, up to the dorsum, laterally to the female atrium, and approaching anteriorly to the female canal. The other outstanding peculiarity is the presence of the massive sphincter ventrally to male and female atria, a feature that is not only unique for a Choeradoplana species , but also unique among known Geoplaninae species. The two peculiarities of the genital anatomy reinforces Froehlich’s (1955) statement that the copulatory apparatus of Choeradoplana is of a simple type, but shows high variation in the details.

Figures

Figure 9. Choeradoplana banga sp. nov. Holotype initiating movement. About 30 mm in length.

Figure 10. Choeradoplana banga sp. nov. Holotype. Diagrammatic transverse section of prepharyngeal region. Scale bar 0.5 mm.

Figure 11. Choeradoplana banga sp. nov. Holotype. Diagrammatic represention of the pharynx from sagittal sections. Scale bar 1 mm.

Figure 12. Choeradoplana banga sp. nov. Holotype. Diagrammatic representation of the copulatory apparatus from sagittal sections. Only one-side half of the prostatic vesicle represented. Scale bar 1 mm.

Figure 13. Choeradoplana banga sp. nov. Holotype. Micrograph of a sagittal section of the massive sphincter ventral to the male and female atria. Scale bar 0.5 mm.

Figure 14. Choeradoplana banga sp. nov. Paratype MZUSP PL 1001. Diagrammatic representation of the copulatory apparatus from sagittal sections. Only one-side half represented. Scale bar 1 mm.

Figure 15. Choeradoplana banga sp. nov. Paratype MZUSP PL 1001. Micrograph of a sagittal section of the copulatory apparatus. Scale bar 1 mm.