Nygulgus evelinae Marcus 1954

Autor: Brusa, Francisco, Damborenea, Cristina, Nore��a, Carolina
Rok vydání: 2008
Předmět:
DOI: 10.5281/zenodo.5618728
Popis: Nygulgus evelinae Marcus 1954 Figures 6, 8 E. Material and locality. S pecimens in vivo studied by squash method. Twelve specimens sectioned in the sagittal plane, MLP 5365, 5366, Punta Piedras (2��8 ��00, 12 �� 2 ��01, 24 �� 8 ��01; 4 �� 4 ��02; 5 �� 3 ��03). Comments. Live adult specimens were 480 ��m long and 95���115 ��m wide, and fixed specimens were 200 ��m long. Marcus (1954) mentioned that the largest specimens were 500 ��m long and 200 ��m wide, which represents a slightly larger size compared to the specimens studied here. The epithelium of the R��o de la Plata specimens was 4 ��m thick, with a well developed basal membrane and very numerous small rhabdites. The first two features are coincident with Marcus��description (Marcus 1954); however, this author mentioned the absence of rhabdites in the epithelium. The parenchyma of live specimens contains symbiotic algae, greenish brown in color. Marcus (1954) mentioned that the distribution of the symbionts in the parenchyma is variable; however in the studied material the algae were concentrated on the dorsum, from the pharynx to the posterior body.The brain is large, almost the same size as the pharynx. The eyes are located in the anterior region, with large pigment granules arranged around three visual cells (Figure 6 C), in agreement with Marcus��description. The mouth is subterminal, with a sphincter. The buccal tube has ciliated epithelium surrounded by muscles, expanded to form the pharyngeal bursa. The pharynx was 80 ��m long and 40 ��m wide in live Brazilian specimens (Marcus 1954), while the pharynx of Argentine specimens is 44 ��m long. In the same work, this author mentioned that the pharyngeal nuclei are located in the oesophagus, while the nuclei observed in the pharynx correspond to the pharyngeal glands and myoblasts. The pharynx presents a triradiate lumen, continued into the intestine. The latter bears a crown of ���Minot���s gland cells��� at its cephalic end. The male reproductive system consists of two lateral testes located in posterior half of body (figure 6 B); in contrast, Marcus (1954) mentioned that the testes are at pharynx level. One efferent duct issues from the caudal end of each testis, connecting with the seminal vesicle posterior to the pharynx. The ejaculatory duct crosses over the penis papilla, which is wrapped by a thin trumpet��shaped sclerotic stylet. The base of the stylet is formed by two rings; it is 38 ��m long and 16 ��m wide at the level of these rings, and 7.5 ��m wide at its expanded distal end (figure 6 A). The stylet illustrated by Marcus (1954) is slighted shorter than the ones studied here (approximately 30 ��m long and 12 ��m wide proximally, after Marcus 1954, figure 35). The stylet reaches the male region of the atrium rostrally. The atrium opens to the exterior through a mid��ventral gonopore, surrounded by a sphincter. The morphology of the female reproductive system agrees with the original description (Marcus 1954), comprising a pair of ovaries located near the caudal body, and partially covered by two dorsal vitellaria. The germinative region of the ovaries has rostro��ventral position, and the ovocites become mature towards the caudo��dorsal region. The oocytes are arranged biserially in the germination zone, and uniserially at mature stage. Two short ovovitelloducts open into the female region of atrium. The proximal atrium functions as uterus. Spermatozoids were frequently observed in both uterus and bursa; these structures are separated by a sphincter. The bursa is thin in young specimens and communicates with the intestine; this connection disappears in adults. The bursa functions as bursa resorbiens and the uterus acts as seminal receptacle (Marcus 1954). A gland, sometimes lobulate, with eosinophilic secretions, opens on the ventro��caudal wall of the uterus. Previously known distribution. Brazil: mangrove swamp at the estuary of Itanhaen River (50 km southwest from Santos) (Marcus 1954). This is the first record of this species in Argentina, as well as the first citation after its original description.
Published as part of Brusa, Francisco, Damborenea, Cristina & Nore��a, Carolina, 2008, " Dalyellioida " (Platyhelminthes, Rhabdocoela) from the R��o de la Plata estuary in Argentina, with the description of two new species of Gieysztoria, pp. 1-16 in Zootaxa 1861 on pages 12-13, DOI: 10.5281/zenodo.183668
{"references":["Marcus, E. (1954) Turbellaria brasileiros XI. Papeis Avulsos do departamento de Zoologia. Secretaria da Agricultura. Sao Paulo, 11, 419 - 489."]}
Databáze: OpenAIRE
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