Brinkhurstia americanus ( Brinkhurst 1964 )

Jamieson, Barrie G. M. & Fragoso, Carlos, 2024, A monograph of the Oligochaete family Alluroididae, Zootaxa 5529 (3), pp. 401-435 : 421-422

Brinkhurstia americanus ( Brinkhurst 1964) (See Figs 3 & 10 )

Alluroides americanus nom. nud. Cernosvitov 1936: 19.

Alluroides americanus Brinkhurst 1964: 533–534 . Figs.5–7 .

Brinkhurstia americanus (Brinkhurst) , Jamieson 1968: 80–81, Figs. 3 , 12 ; Brinkhurst & Jamieson 1971: 716–717, Fig. 14.1E, F; Righi et al. 1978: 11–12, Figs. 11 –21; Stacey & Coates 1996: Tables 1 and 2; Omodeo and Coates 2001: 39–40, Fig. 1 A, B.

Length 24–30 mm, width 0.56–0.75 mm, segments 100–130. Prostomium short or large and rounded. Ventral setal couples of XIII replaced by a single penial seta on each side; in the ovarian segments aa:ab:bc:cd:dd =4.7:1:5:1.1:6.2; dd =0–25 u; length of a lateral seta from XI, base to node=87 µm. Clitellum annular, slightly less developed ventrally; segments 1/2XII–XV. Lateral lines present. Male pores ventrolateral in XIII. Female pores anterior in XIV. Spermathecal pore single, middorsal, anteriorly in IX.

Septum 3/4 excessively delicate and doubtfully complete; 4/5 and 14/15 hardly appreciably, 6/7–8/9 fairly strongly thickened (two tiers of muscle fibres) the remainder intermediate; 10/11 has one tier of muscle fibres and is not backwardly deflected. Septal glands in V–VIII. Alimentary canal expanding greatly in XVI but no definite transition from oesophagus to intestine. Gizzard, oesophageal diverticula and typhlosole absent. Perienteric blood sinus in IX posteriad, not appreciable in front of this. Testes discrete elongated tongues of tissue dependent from the anterior wall of X. Gonadial tissue absent from XI. Seminal vesicles absent or present in XI. Vas deferens running on body wall in XI and XII. Atria very thin much coiled tubes extending from mid–XIII into XIV; discharging in the close proximity of the corresponding vas deferens through the posterior wall of a globular non-muscular ectal chamber; a simple, straight, unornamented penial seta in a follicle approximately twice the length of the chamber, penetrates the anterior wall of the chamber. Each prostate has a cuboidal lining epithelium surrounded in turn by a very thin muscular sheath and an external layer of prostatic cells only one to a few cells thick, though considerable masses of prostatic cells are formed between adjacent coils. Width muscular tube of atrium (external) 28 µm; width ectal chamber 37 µm; length penial seta 115 µm; greatest width 18 µm. Ovaries dependent from the anterior wall of XIII and extending posteriad into ovisacs formed by the backward evagination of septum 13/14 through as many as 8 segments: diameter of the largest oocyte–nuclei 33 µm. First nephridia (from peritoneal masses) in IX or X. Spermatheca in IX a simple elongated pouch, 87 µm wide, with no distinct ampulla, lined internally by a short columnar epithelium invested in a single layer of circular muscle and an outer glandular? peritoneal sheath.

Distribution. Brazil; Saint Lucia (Caribbean); Argentina; Guyana.

Figures

FIGURE 1A. Hennigram (morphological phylogram) for all families of the opisthoporous oligochaetes constructed by nearestneighbour clustering. For details see Jamieson (1978). Redrawn.

FIGURE 3. Brinkhurstia americanus (Brinkhurst 1964). Longitudinal section through the male terminalia. at.ch, terminal chamber of atrium; at.d, atrial duct; gl.sh, glandular sheath; m.sh, muscular sheath; o.v, ovary; pro, protractor muscle; p.s, penial seta; re, retractor muscle; sep, septum; v.d, vas deferens. From Jamieson (1968).

FIGURE 5. Alluroides brinkhursti brinkhursti Jamieson (1968). A. Transverse section (TS) of clitellum, showing single cell layer; the cells with conspicuous secretory granules and each with a basal nucleus. B. TS through the wall of the atrium, showing a group of atrial gland cells with ductule penetrating the muscular sheath of the atrium. C. Longitudinal section through the male pore, showing the ectal end of the atrium, which forms a penis with muscular sheath, ciliated epithelium and rope of spermatozoa in the lumen, forming in the ectal chamber a sperm mass. D. Alluroides pordagei. Oblique section through the atrial bulb, containing a large sperm mass, and the associated atrium. From Jamieson (2006).

FIGURE 6. Alluroides brinkhursti abyssinicus Jamieson (1968). Longitudinal section of holotype. Abbreviations: epi, epithelium of atrium; gl sh, glandular sheath of atrium; m, mouth; msh, muscular sheath of atrium; oe, oesophagus; oo, oocyte: ph m, pharyngeal musculature; s.ves, seminal vesicle; sp, spermatheca; vbv, ventral blood vessel; vd, vas deferens; v n, ventral nerve cord. Slightly modified from Jamieson (1968).

FIGURE 7. Alluroides lauzannei Ljungström, 1971. Detail of an atrium. Note the vas deferens entering the apex of the atrium via canaliculi. Relabelled from Lauzanne (1968).

FIGURE 10. Brinkhurstia americanus. (Brinkhurst 1964). Spermatheca opening mid–dorsally in the anterior of IX. Abbreviations: a, ampulla; cv, commissural vessel. From Omodeo & Coates (2001), reproduced with permission.

FIGURE 11. Brinkhurstia donaldi Omodeo and Coates (2001).A. Scheme showing arrangement of genital organs and vascular commissures. B. Cross section through spermathecal duct. C. Cross section of the muscular sac ensheathing penial seta. D. Section through ental part of prostate. E. Cross section of prostatic duct. F. Dorsal view of the arrangement of the penial setae within IX–XIII. Abbreviations: a, spermathecal ampulla, cv, commissural vessels, d, spermathecal duct, di, spermathecal diverticulum, e, egg, if‚ female funnel, md, male duct, pc, penial seta, pr, prostate. From Omodeo & Coates (2001), reproduced with permission.

FIGURE 12. Brinkhurstia donaldi Omodeo & Coates 2001. Spermatheca, sagittal section. Abbreviations: a, ampulla; d, duct; di, diverticulum; se, septum with muscle fibres; spz, spermatozoa; ss, sponge spicules. From Omodeo and Coates (2001), reproduced with permission.

FIGURE 14. Lacandodrilus paludosus Fragoso & Rojas 2023. A. External view of the anterior ventral region of a clitellate adult. B. Internal view of the anterior region of an adult. C. Spermatheca. Abbreviations: a, ampulla: clit, clitellum; d, duct; dv, dorsal vessel; gg, genital glands (prostates?); img, internal male gonoducts; mf, male funnels; n, nephridia; oe, oesophagus; sg, septal glands. Modified from Fragoso & Rojas (2023).