Guestphalinus wiardi ( Michaelsen, 1933 )

Fend, Steven V., Rodriguez, Pilar, Achurra, Ainara & Erséus, Christer, 2017, On Kincaidiana Altman, 1936 and Guestphalinus Michaelsen, 1933 (Annelida, Clitellata, Lumbriculidae), with the descriptions of three new species, European Journal of Taxonomy 361, pp. 1-46 : 20-22

Guestphalinus wiardi ( Michaelsen, 1933)

Fig. 6

Dorydrilus (Guestphalinus) wiardi Michaelsen, 1933: 7 , figs 1–2.

Questphalinus wiardi – Hrabě 1936: 10; 1973: 45, figs 4–6.

Guestphalinus wiardi – Cook 1968: 281, fig. 2e; 1971: 237. — Dembitsky 1987: figs I–III.

Material examined

SLOVENIA: a single specimen, sagittally sectioned on 3 slides, near Dornberk (Czech National Museum (Prague), Hrabě collection, 1970–25 I 1–3).

ITALY: a sagittally dissected anterior end, Grotta Sulfurea, Frassasi Cave system, Genga/Ancona, 43.401° N, 12.966° E, Marche, Sharmishtha Dattagupta and Jennifer L. Macalady leg., Jun. 2007.

Description of new material and remarks

Hrabě (1973) described a mature, unmated specimen from Slovenia, with sperm on the male funnels. This specimen from Hrabě’s collection is reexamined here, but only the anterior body section was available. The figures in Hrabě (1973: figs 6–7) correspond to photographs 6B and 6C, respectively, in the present paper (note that labels for spermathecal and male pores should be reversed in Hrabě: fig. 6). The Italian specimen is mature, with clitellum from VIII–XIII and sperm in the spermathecae; the anterior 100 segments are represented. Descriptions by Michaelsen (1933) and Hrabě were quite detailed, and were reviewed by Dembitsky (1987); nevertheless, we can add the following remarks based on both specimens.

A pair of lateral blood vessels is visible in posterior segments of the Italian specimen, and some of these have a few blind branches ( Fig. 6I ). Chaetae in anterior segments are simple-pointed, but tips of most chaetae in posterior segments bear a distinct dorsal groove, which may appear as a small dorsal tooth in lateral view ( Fig. 6F ).

The anterior vasa deferentia form a loop in the pre-atrial segment (VIII) before penetrating 8/9 and entering IX to join the atrium ( Fig. 6A, E, G ) in both of our specimens; this unique character was described and illustrated by Michaelsen (1933), but not mentioned in later descriptions. Posterior vasa deferentia do not penetrate septum 9/10. Michaelsen (1933) described and illustrated a greatly expanded posterior sperm funnel extending well into the posterior sperm sacs. Both posterior and anterior male funnels are small in the Slovenian worm ( Fig. 6A ); they are much larger in the Italian specimen, and the posterior extends back into X ( Fig. 6G ). Vasa deferentia are very thick (to 50 µm) in the Italian worm, joining the atrium subapically; they join the atrium before the apex in the Slovenian worm, running a short distance under the muscle layer to enter the lumen apically, as described by Dembitsky (1987) for Crimean specimens. Compared with other descriptions, the atrial ampulla appears rather short and ovate in the Slovenian and Italian worms, although the total atrium length (320 and 335 µm, respectively) and width are similar to those of the Crimean specimens ( Dembitsky 1987). Male pores are on a rounded protrusion (referred to as a porophore by Michaelsen 1933), closely behind a groove containing the spermathecal and copulatory gland pores in the Slovenian worm ( Fig. 6 A–B). Although this structure was also illustrated by Dembitsky (1987: fig. III) it was not seen in our Italian specimen ( Fig. 6G ). Prostate glands are large (to about 100 µm high), petiolate clusters of cells, more similar to fig. 2 in Michaelsen (1933) than to fig. III in Dembitsky (1987).

The large copulatory glands ( Fig. 6C, H ) are quite similar in structure to the copulatory glands described below in the new Nearctic species, although a distinct muscle layer was not seen at the duct. The illustration in Hrabě (1973: fig. 7) is similar to ours. The slight difference in placement (adjacent to the spermathecae in both of our specimens), compared with Michaelsen’s material (at the ventral chaetae), suggests that the position of these glands may be variable, as in Guestphalinus exilis Fend & Rodriguez sp. nov. (see below). Their occurrence may also vary with stage of reproductive development, as Dembitsky (1967) was unable to find these glands in the Crimean specimens, attributing their absence to possible resorption.

The spermatheca is not clearly differentiated into duct vs ampullar sections, although there is a sphincterlike constriction, with thickened circular muscles near the pore of the Slovenian worm ( Fig. 6D ). The female funnel is clearly visible only in the Italian worm ( Fig. 6G ), where it appears to penetrate the posterior septum 10/11 (the plesiopore condition), as in the illustration in Michaelsen (1933). Guestphalinus was the only lumbriculid genus considered by Brinkhurst (1989: character 16) to have plesiopore female ducts, in common with Haplotaxis , one of the outgroup taxa in that analysis. However, this character has not been observed in G. elephantinus sp. nov. nor in G. exilis sp. nov., where female pores appear to be intersegmental (see below, Fig. 12Q ). Plesiopore female ducts appear to be unusual in the Lumbriculidae ( Brinkhurst 1989; Fend & Ohtaka 2004), but they may simply have escaped notice in other species descriptions. The exact position of the septum may be difficult to define, as muscle fibers from septa may join the body wall on either side of the female funnel.

Figures

Fig. 6. Guestphalinus wiardi (Michaelsen, 1933); A–E a sectioned worm from Slovenia, Hrabě’s collection; F–I, a dissected Italian specimen. A. Male duct and spermatheca in IX, reconstructed from sections; pore from a copulatory gland (not shown) opens next to spermathecal pore. B. Atrium and male porophore. C. Copulatory gland. D. Spermathecal pore and duct. E. Anterior male funnel with vas deferens entering pre-atrial segment. F. Posterior ventral chaeta, showing grooved dorsal tooth. G. Reproductive organs in IX-XI, figure rotated to face to right. H. Detail of G, showing position of copulatory gland, from median view. I. Branched lateral blood vessel in posterior segment. Scale bars: A, G–H = 200 Mm; B, E, I = 100 Mm; C–D, F = 50 Mm.

Fig. 12. Guestphalinus elephantinus Fend & Rodriguez sp. nov.A–B (upper) from Clearwater River, WA; C, H, K from Shale Creek, WA (type locality); D–E from Satsop River, WA; B (lower), F–G, N–Q from Guadalupe Creek, CA; I–J, L–M from Peavine Ridge, OR. A. Anterior end of cleared worm. B. Chaetae in II-III, comparing worms from northern (upper) and southern (lower) populations. C. Dorsal chaetae in II. D. The outer chaeta in II, showing the “secondary nodulus”. E–F. Inner dorsal chaeta in II; E shows folded keel. G. Modified dorsal chaetae in II. H. Posterior ventral chaeta. I. Posterior ventral chaeta with bifid tip. J. Transverse section of anterior segment, showing lobes of pharyngeal glands. K. Body wall in anterior segment. L. Spermathecal pore. M. Male pore. N. Ectal part of spermatheca from a dissected, mated worm. O. Expanded atrial duct (type 2 penis?) at male pore. P. Copulatory gland. Q. Female funnel and pore on intersegment 10/11. Scale bars: A = 1 mm; B–I, K–M = 50 µm; J, N–Q = 100 µm.