Hemienchytraeus tanjae, Schmelz & Römbke, 2005

Schmelz, R. M. & Römbke, J., 2005, Three new species of Hemienchytraeus (Enchytraeidae, Oligochaeta) from Amazonian forest soil, Journal of Natural History 39 (32), pp. 2967-2986 : 2976-2979

publication ID	https://doi.org/ 10.1080/00222930500218664
persistent identifier	https://treatment.plazi.org/id/03E3594E-5842-0261-6DBC-0285A8C2FB1C
treatment provided by	Felipe
scientific name	Hemienchytraeus tanjae
status	sp. nov.

Treatment

Hemienchytraeus tanjae View in CoL sp. nov.

( Figure 3 View Figure 3 )

Type material

Holotype: INPA 125 View Materials , stained and whole-mounted specimen, fully mature, coll. December 2000 . Paratypes: INPA 126 View Materials , four specimens , coll. December 1997 (four specimens); ZIM OL 14284 View Materials , four specimens , coll. December 1997 (one specimen), December 2000 (three specimens). All paratypes stained and whole mounted, fully mature.

Description

Length ca 5 mm (viv) or 4–5 mm (fix), diameter 0.125 mm (viv) or ca 0.12 mm, up to 0.15 mm in XII/XIII, down to 0.1 mm in terminal segments (fix). Segment number 31–34. Segments following clitellum 2–3× as long as wide when stretched, segments shortening towards posterior end. Two chaetae per bundle throughout, present laterally in XII also in mature specimens. Chaetae without nodulus, pointed distally, blunt proximally, only faintly sigmoid, distal curve rather slight, often inconspicuous ( Figure 3C View Figure 3 ). Chaetae only slightly enlarged in posterior segments; ventrals 28 mm long and 2.5 mm thick in anterior segments, 33 mm long and 3 mm thick in terminal segments. Head pore ( Figure 3A View Figure 3 ) on prostomium in form of a small transverse slit. Epidermal gland cells in three to four rows in preclitellar segments, more cells on dorsal half than on ventral half; in posterior segments one row per segment at chaetal level.

Clitellum ( Figure 3D, E View Figure 3 ) girdle-shaped, i.e. fully developed ventrally, and short, i.e. extending over little more than one segment length, ending at some distance before chaetae of XIII; cellular arrangement reticulate or in indefinite rows on all sides except ventrally; hyalocytes about twice as wide (diameter ca 20 mm, viv) as granulocytes (diameter ca 12 mm, viv); difference more marked in fixed specimens. Hyalocytes largest in specimens with fully developed egg ( Figure 3D View Figure 3 ). Ventrally, in a field as wide as the distance between bursal slits, only granulocytes, arranged in dense transverse rows, clitellum less elevated here.

Body wall usually 4–5 mm thick, up to 10 mm ventrally in preclitellar segments (fix), cuticle thin (, 1 mm), preclitellar septa not thickened. Brain ( Figure 3A, B View Figure 3 ) ca twice as long as wide (e.g. 65 mm × 35 mm, fix), deeply incised anteriorly, slightly indented posteriorly, sides parallel or slightly converging anteriad. Post-pharyngeal bulbs conspicuous ( Figure 3B View Figure 3 ). Ventral nerve cord perikarya concentrated in segmental ganglia from V on, i.e. no perikarya in the region of the septa. Oesophageal appendage ( Figure 3A, B View Figure 3 ): unpaired root with moderately large proximal chamber; root and primary branches of about equal length and equal canal width. Two secondary branches on each side, short, with narrow canal lumen. Diameter of appendage decreasing from unpaired root over primary to secondary branches. Pharyngeal glands ( Figure 3A, B View Figure 3 ) all united dorsally in IV, V and VI, connection widest in IV, narrow in VI; primary ventral lobes in V and VI, secondary ventral lobes in V, small, attached to septum 4/5, apparently absent in one specimen. Efferent fascicles ( Figure 3B View Figure 3 ) not conspicuously enlarged. Chloragocytes as a thin layer from V, filled with light brown vesicles (same colour as gut contents). Dorsal blood vessel from XIV. Inflated ventral gut epithelium inconspicuous, from 1/2 XIX–XXI, only slightly higher than epithelium in adjacent anterior and posterior segments, higher than dorsal epithelium in same segments, recognizable mainly by granular texture and less intensive staining in fixed specimens .

Nephridia ( Figure 3A, F View Figure 3 ) in preclitellar segments: four pairs, from 5/6 to 8/9; anteseptale globular, with minute and numerous brownish granules at periphery; funnel orientated obliquely ventrad, with small and narrow anterior projection; postseptale elongate, ca twice (1.7–2.5×) as long and about as high as anteseptale; length of nephridia 50–85 mm (fix), mostly subterminal rise of efferent duct (also medial and terminal); terminal vesicle small, inconspicuous. Postclitellar segments: first pair at 14/15, nephridia reduced in number in following segments, often unpaired, many segments without nephridia; nephridia in posterior body half larger than in preclitellar segments, longer (up to 140 mm, viv) than body diameter, shape as in preclitellar segments, with mostly terminal rise of efferent duct. Coelomocytes small, length ca 15 mm (viv, fix: 12–16 mm), longer than wide; colour pale, margin wavy, texture with blurred vesicles (viv); cells not numerous, often aggregations postero-dorsally in V, VI and VII and in terminal segments.

Seminal vesicle absent. Few sperm on top of sperm funnel collar, spermatozoa longer than funnel (ca 70 mm, fix), heads short. Sperm funnel ( Figure 3E View Figure 3 ) small, ca twice as long as wide, less than half as long as body diameter (e.g. 53× 22 mm, viv, 50× 19 mm, fix), funnel body as wide as or narrower than collar, tapering distad. Vas deferens in XII, usually coiled in small, irregular, consecutive loops ventro-laterally; diameter 3 mm (fix). Male copulatory organ ( Figure 3E View Figure 3 ): glandular body globular, diameter 24–28 mm (fix), bursal slit longitudinal (viv), staple-shaped or broadly U-shaped in fixed specimens, shorter than diameter of glandular body. Accessory copulatory glands absent.

Spermatheca ( Figure 3A, B View Figure 3 ) inconspicuous, often difficult to see (viv, fix), extending into VI or VII, consisting of ectal duct and ampulla, the latter subdivided into ectal dilatation, connecting tube and ental reservoir. Ectal dilatation not seen in all specimens, here ectal duct continuously merging into connecting tube. Ectal duct ca one segment length long, canal and wall epithelia of about the same diameter; ectal pore 2–3 mm wide (fix), up to 4 mm in living specimens, canal lined with cuticle distally, cuticle thinning out proximad. Ectal dilatation of ampulla 10–12 mm wide (fix), connecting tube with inconspicuous canal, ental reservoir thin-walled, 13–15 mm wide (fix). Sperm present in ectal dilatation and ental reservoir; in ectal dilatation, sperm arranged side-by-side in a wisp with nuclei orientated distad and flagella extending straight into proximal tube; in ental reservoir, spermatozoa arranged in a dense and irregular coil. One mature egg at a time, extending over two to three segments when fully developed.

Remarks

The secondary pharyngeal gland lobes are quite small, and apparently absent (i.e. not seen) in one of the paratype specimens. Other characters (especially details of oesophageal appendages, nephridia, and clitellum) are without exception. Two further specimens found at the type locality, one submature, one juvenile, agree with the diagnosis of H. tanjae in the pattern of pharyngeal glands (one pair of secondary lobes in V) and in the distribution of preclitellar nephridia (four pairs, from 5/6 to 8/9). However, the secondary pharyngeal gland lobes are large and conspicuous, terminal chaetae are almost twice as large as preclitellar chaetae and the submature specimen is larger (body diameter 0.225 mm, fix) than mature specimens of H. tanjae . In view of the clearcut differences it would seem unjustified to include these specimens into H. tanjae . Their identity must remain uncertain until more and mature material has been found.