Sperber, Christina. (1948). A taxonomical study of the Naididae. Zoologiska Bidrag från Uppsala. 28: 1-296.
279795
Sperber, Christina
1948
A taxonomical study of the Naididae.
Zoologiska Bidrag från Uppsala
28: 1-296
Publication
A published dissertation
Available for editors
Summary. In order to achieve a conception of the taxonomy and phylogenetical relationships of the Naidiclae, comparative morphological studies have been carried out on 37 Swedish species, and the facts available in the literature on the family have been extracted. Observations have been made on living material, and from preserved specimens, mounted whole or sectioned. The following organs have been· chosen for more thorough examination, being most useful for taxonomical purposes in the family: the setae, the alimentary canal, the vascular system, and the sexual organs. Summaries of the appearance of these organs in ·the different genera and species are given in the general section. Here the general histology of the alimentary canal and the ·genital organs are also described. The gland cells on the pharynx and oesophagus usually consist of two sorts, here called pharyngeal and oesophageal gland cells, the former occurring on the pharyngeal diverticulum, the latter mainly behind this, on the oesophagus; instead of this type, septal glands may be present, which are probably derived from the oesophageal gland cells. The pharyngeal gland cells are connected with the pharyngeal lumen, into which their secretion, staining like mucus, is poured. A stomach has been found in all the species examined; the epithelium is usually invested with a brush border and cilia (special features are found in the Chaetogastrinae, the Pristininae, and Paranais litoralis). Probably all Naids have a stomach, though not necessarily marked off by a dilatation. The intestinal epithelium is also invested with a brush border and cilia. The dorsal vessel runs ventrally, to the left of the intestine, in Specaria and Piguetiella, besides the cases reported in the literature. It is decidedly left-sided, though not ventral, in a number of cases. In Specaria josinae there are not commissural vessels in all segments, as stated in the literature. Commissural vessels in newly-budded posterior segments were reported by Bourne (1890) in Paranais litoralis; such are also found in P. botniensis and Dero digitata. The clitellum consists of a layer of tall glandular cells, each of which contains, in the mature condition, one large vacuole filled with secretion globules staining like the cocoon-wall, a basal nucleus, and very little cytoplasm; between these are extremely narrow "supporting" cells with distal nuclei. The clitellum is often absent or has a different appearance, round and between the male pores. Definite gonads are found in Chaetogaster as well as in other Naids. The atrial epithelium in Stylaria (and other genera with atrial prostate) is glandular; it does not lose its cell-borders and disintegrate, contrary to the statements by Mehra (1920). In the special section, the diagnostic features of each systematic unit have been shortly summarized. The synonymy of each species has been discussed, where it has not been wholly clear. For personally investigated species, descriptions are given of details of taxonomical interest, which were not, or only unsatisfactorily, described earlier, and measurements of setae and sexual organs (when met with) are given. Three new species are described: Paranais botniensis, Nais alpina, and Pristina idrensis. The genus Paranais is divided into three: Paranais (with dorsal setae from V on, septal glands, no nephridia, only 4 segments formed anteriorly on budding, and genital organs situated in IV-V, no prostate being present, vasa deferentia entering the atria distally, and clitellum being present round the male pores), Homochaeta (with dorsal setae beginning in II, no prostate, but vasa deferentia opening into the proximal end of the atria, and atria and spermathecae without ducts, the former opening into an invagination), and Uncinais (with dorsal setae from VI, eyes, and prostate on the vasa deferentia, which open distally). The genus Nais has been divided into two: Nais and Allonais (the latter comprising species without eyes, stomachal dilatation and prostate, usually with an anterior vascular plexus and additional loops, propagating asexually by architomy). The genus Dero has been divided into two subgenera: Dero and Allodero (with the species A. malayana, bauchiensis, and lutzi), Aulophorus being added as a third subgenus. The phylogenetical interrelations between the genera of the family have been discussed, as well as the relations to some other Oligochaete families. The genera Chaetogaster and Amphichaeta are closely related to each other, together forming an independent branch of the family; they have been separated as the subfamily Chaetogastrinae. Likewise the peculiarities of Paranais and Pristina respectively, indicate that these genera have branched off early from the common stem (cf. the scheme, p. 260). They have been separated as the subfamilies Paranaidinae and Pristininae from the rest, the Naidinae. Very probably Stephensoniana ought also to form a subfamily, but owing to the present imperfect knowledge of the genus, a separation has not been undertaken. The Tubificidae are no doubt the closest relatives of the Naididae but neither of these families can be derived from the other. The Aeolosomatidae are apparently very primitive in many respects, and not closely related to the Naididae or any of the other Oligochaete families.
