Amaga amagensis ( Fuhrmann, 1914 )

Grau, José Horacio, Sluys, Ronald, Froehlich, Eudóxia Maria & Carbayo, Fernando, 2012, Reflections on the genus Amaga Ogren and Kawakatsu 1990, and description of a new genus of land planarian (Platyhelminthes: Tricladida: Geoplanidae), Journal of Natural History 46 (25 - 26), pp. 1529-1546 : 1531-1533

Amaga amagensis ( Fuhrmann, 1914)

Material examined

Type material: NHM 1928.1.4.83–88 + 1928.1.4.90–91 + 1928.1.4.112 + 1928.1. 4.92–95, sagittal sections of the pharynx and copulatory organs; 1928.1.4.110–111 + 1928.1.4.113 + 1928.1.4.89 + 1928.1.4.114–115, sagittal sections of the posterior end of a second animal; 1928.1.4.96–109, transversal section of pre-pharyngeal region; 1928.1.4.116–120, horizontal sections of the anterior end; Cafetal la Camelia , south of the Amagá river valley, Colombia, altitude 1600–1800 m (note that there is a mix up in the numbering and assignment of slides to specimens concerning the two sagittally sectioned animals; the order given above represents the original, continuous series of sections) .

Description

Body height 1800 µm. Creeping sole wide and ciliated, up to 90% of the body width in transverse sections ( Figure 1A ).

Eye cups distributed anteriorly in a single row; diameter of the pigment cup ranging from 40 to 60 µm. In the pre-pharyngeal region the eyes extend marginally in irregular rows. Sensory pits inconspicuous in anterior part, absent in pre-pharyngeal region. Nervous system arranged in a flat nerve plexus.

Xanthophil secretions open to the exterior at the margins of the body, forming a glandular ridge or margin ( Figure 1A,C ). Rhabdite-forming cells are distributed in the dorsal parenchyma. Epidermal cells of the dorsal body surface densely packed with rhabdites; ventral epidermis sparsely provided with small rhabdites. The dorsal epidermis (30 µm) is thicker than the ventral epidermis (20 µm).

Subepidermal musculature tripartite, composed of circular, double diagonal and longitudinal layers. Longitudinal layer packed in small, separate bundles, stronger dorsally (60–75 µm high) than ventrally (40–50 µm high). In the anterior region the subepidermal musculature has the same arrangement as in the rest of the body, so does not exhibit any specialization. Parenchymal musculature weak, composed of a few thin, obliquely running fibres, and other fibres arranged in three layers: supraintestinal and subintestinal transversal layers, and a dorsal double layer of diagonal fibres. Longitudinal parenchymal muscle fibres absent.

Pharynx incompletely present in the type material. Mouth located at least 5.6 mm from the posterior end of the pharyngeal pouch. Pharynx of the collar-type, long and flat and highly folded. Oesophagus not observed, as the root of the pharynx was not present in the slides of the type material. Pharyngeal pouch mainly surrounded by circular muscle fibres, with a few interspersed longitudinal fibres. Outer pharynx epithelium ciliated. Outer pharyngeal musculature composed of thin layers of intermingled longitudinal and circular muscles. Inner pharyngeal musculature not observed, as only the external pharynx layers were sectioned.

The globular testes measure about 200 × 320 µm. The testes are located dorsally and placed above the parenchymal supra-intestinal transversal muscle layer ( Figure 1A,B ). The follicles are arranged in multiple irregular rows on each side of the pre-pharyngeal region of the body. Vasa deferentia densely filled with spermatozoa. Each vas deferens communicates terminally with one of the branches of the bifurcated prostatic vesicle ( Figure 2A,B ). Prostatic vesicle anteriorly bifurcated with two long branches (about 2.1 mm long) ( Figure 2A,B ). From the point where the two branches unite, the prostatic vesicle curves anteriad and subsequently posteriad and penetrates the common muscular coat of the copulatory apparatus. The tubular prostatic vesicle is lined with a cuboidal, nucleated and ciliated epithelium. It is surrounded by a thick (20–25 µm) layer of intermingled longitudinal and circular muscle fibres ( Figure 6B ). The prostatic vesicle is surrounded also by brownish, granular secretions, which are discharged into its proximal section. Upon penetrating the muscular coat of the copulatory apparatus, the prostatic vesicle communicates with the ejaculatory duct. The latter is lined with cuboidal, nucleated and ciliated cells and is surrounded by a thin layer of circular muscles. The penis is of the eversible type, consisting of an irregular fold traversed by the ejaculatory duct and is covered by a cuboidal, nucleated epithelium, which is underlain by a layer of circular muscle. In one specimen the penis is everted ( Figure 2B ) and has a globular shape. In the other specimen the penis is not everted and has a small penial fold ( Figure 2A ).

The male atrium consists of an irregularly and elaborately folded cavity, with most folds located at the dorsal side of the atrium. Male atrium about 1.5 times longer than female atrium and surrounded by orange–brown granular secretions that are discharged through its epithelium. Male atrium lined with a squamous, non-ciliated and nucleated epithelium, which is underlain by a weak layer of circular muscles. Glands that are stained dark purple discharge their secretion through the epithelial lining of the gonopore. The common muscular coat that envelopes the male and female copulatory apparatus is composed of loosely arranged fibres

The vitellarian follicles are located dorsally and ventrally to the intestinal branches. Ovaries are placed 1.1 mm from the anterior tip, measuring about 500 µm in dorsoventral direction and 250 µm in width. Ovaries embedded in the transversal subintestinal parenchymatic muscle layer. Oviducal tubes not conspicuous. Ovovitelline duct emerges from the ventrolateral part of each ovary. At the level of the gonopore the ovovitelline ducts ascend at a 45 ◦ angle towards the dorsal body surface and eventually open separately into the vagina. Just before communicating with the vagina, the oviducts receive the secretion of shell glands. The nucleated epithelium of the oviducts is surrounded by a thin layer of circular muscles. The female atrium consists of a cavity lined with a nucleated, non-ciliated epithelium. The vagina emerges from the posterodorsal section of the female atrium and curves anterodorsally, attaining a somewhat horizontal orientation.

Figures

Figure 1. Amaga amagensis. NHM 1928. (A) Transverse reconstruction of pre-pharyngeal region. (B) Transverse section of pre-pharyngeal region, showing dorsal position of testes. (C) Transverse section of glandular ridge. See text for abbreviations.

Figure 2. Amaga amagensis. NHM 1928. (A) Sagittal reconstruction of copulatory apparatus of specimen B. (B) Sagittal reconstruction of copulatory apparatus of specimen A. See text for abbreviations.

Figure 6. (A) Bogga bogotensis. ZMA V.Pl. 6904.1, sagittal section of secretory papillae. (B) Amaga amagensis. NHM 1928, sagittal section of branch of prostatic vesicle. (C) Bogga bogotensis. Holotype, sagittal reconstruction drawing of position of the ovaries. (D) Bogga bogotensis, ZMA V.Pl. 6904.1, sagittal section of secretory papillae. See text for abbreviations.