Piguetiella
Piguetiella Sperber, 1939 (ref. ID; 1257, 3692, 7854)
Family Naididae (ref. ID; 5939, 7854)
Family Naididae: Subfamily Naidinae Lastockin, 1924 (ref. ID; 1257)
- Piguetiella amurensis Sokolskaja, 1958 (ref. ID; 3692, 7854)
- Piguetiella blanci (Piguet, 1906) (ref. ID; 1257, 1861, 3692)
- Piguetiella michiganensis Hiltunen, 1967 (ref. ID; 6651, 7854) reported author and year? (ref. ID; 5939)
Descriptions
Length 3-7 mm, width under the cover glass 0.3 mm. Mostly chains with two zooids, the first zooid consisting of 24-28 segments in Lake Bol'soe but only 18 in one individual from the River Razdol'naja. The second zooid can have 22-39 segments plus the terminal growth zone. The single budding zone was always very short, never revealing developed head of the second zooid. Short conical prostomium equipped with eyes. Ventral chaetae in II usually 4 per bundle, in III-V 2, and further backwards 2-4. Those of II-V slightly thinner than the rest, and with upper tooth considerably longer. Beginning from VI, ventral chaetae become thicker, their teeth being of equal length but lower one thicker. The length of ventral chaetae measured 65-103 µm in II-V and slightly more, 84-112 µm, posteriorly. Dorsal chaetae began in VI or VII in specimens from the River Razdol'naja but in VIII-XII in the material from Lake Bol'soe. Every dorsal bundle consisted of bifid chaeta with upper tooth longer and straighter, and a slightly thinner and longer, bent hair chaeta. Dorsal bifids measured usually 84-107 µm (but sometimes only 54-68 µm in the foremost bundles), hair chaetae, 89-137 µm. Pharyngeal glands weakly developed, oesophagus thin, leaving body cavity in anterior segments empty and transparent. A thin layer of dark chloragogen cells covering oesophagus in VI-VII. Intestine begins with abrupt dilatation in VIII. One individual from Lake Bol'soe had a cestode parasite in its body cavity of XXI-XXIII. (ref. ID; 7854)
Remarks
The drawings of chaetae by Sokol'skaja (1958) as reproduced later by Cekanovskaja (1962) and Chekanovskaya (1981) are not informative. The subsequent drawings by Sokol'skaja (1961) are much more characteristic and coincide well with my material. The range of setal length was extended by me. The unusually large segment number of the first zooid (about 50!), noted in the original description, was correctly attributed to the whole animal by Sokol'skaja (1961). I found quite similar total segment numbers, with the first zooid most often consisting of 26-27 segments. Sokol'skaja (1961), in her amended description of the taxon, supposed that anterior dorsal chaetae can easily by be lost during preservation. Thus, the correct beginning of dorsal bundles must be in VI, as was found by her in specimens from the Iman River (belonging to the Amur River system, north of Ussurijsk). The individuals from the Razdol'naja River, studied by me, also had dorsal bundles either from VI, or VII. However, new material from Lake Bol'soe (connected with the Amur River proper) revealed a consistent shift of the beginning of dorsal bundles more backward, to VIII-XII. Moreover, the first dorsal chaetae were usually smaller than the rest, i.e. just developing. Thus, their backward shift seems to be regular in the northern part of the distribution range. The identification of this taxon as a Piguetiella Sperber, 1939 by Sokol'skaja (1958) was, in all probability, wrong. Its dorsal chaetae remind of those of another, monotypic naidid genus, Haemonais Bretscher, 1900. However, eyes are always present in the species amurensis but lacking in Haemonais. The true position of the species will remain open until its reproductive organs are found and studied. (ref. ID; 7854)
Examined materials
River Razdol'naja, 5 species from three localities in Ussurijsk, May-June 1990 and 1992. Lake Bol'soe, connected with the Amur River, 19 specimens collected in July-August 1977 by Vdovcenko, by courtesy of N.A. Zaloznyj (Tomsk). Immatures only, studied as whole mounts. (ref. ID; 7854)
Piguetiella blanci (Piguet, 1906) (ref. ID; 1257, 1861, 3692)
Descriptions
P. blanci feeds on lake sediments, lives in the littoral and sublittoral zones of lakes, especially on mud or muddy sand. (ref. ID; 1861)