Hyperiodrilus africanus Beddard, 1891

James, Samuel W. & Divina, Gildas Brice, 2012, Earthworms (Clitellata: Acanthodrilidae, Almidae, Eudrilidae, Glossoscolecidae, Ocnerodrilidae) of the coastal region of Gamba, Ogooué-Maritime Province, southwestern Gabon, Zootaxa 3458, pp. 133-148 : 146-147

Hyperiodrilus africanus Beddard, 1891

Material. USNM 1180266 , four clitellates, Vembo , Gamba Complex, Gabon gardens around lab buildings at 2.74746°S, 9.99633°E, 10 m asl., 18 and 20 May 2008; S. James, G. Divina, G. Moussavou and L. Tchignoumba, colls .

Description. Dimensions 70–120 mm by 3.2–3.6 mm at segment X, 3.4–4.1 mm at clitellum, 2.8–3.5 mm at XXX; body cylindrical throughout, segments 180–212. Setae AB widely paired, CD closely paired throughout; setal formula AA:AB:BC:CD = 3:1.6:3:1 at X, 4:3:3.5:1 at XXX, DD> 1/2 circumference throughout. Prostomium epilobous with faint paired furrows not quite reaching 1/2, secondary annulation post-setal XI, pre-, post-setal XII, XIII, XIX–XXXV. Dusky gray pigmentation denser dorsally. Nephropores in CD, large. Spermathecal pore midventral, slightly pre-equatorial in XIII. Ovipores paired on trailing edge of XIV in D; male pore mid-ventral in 17/ 18 at angle of V-shaped seminal groove open to anterior. Seminal grooves surrounded by elevated epidermis but greatly thicker at anterior ends of grooves where the elevation forms a papilla; grooves asymmetrical and variable: wide with ends within XVII but one arm longer, or narrower V-shape with one arm longer reaching into XVI, the other only into XVII. Clitellum 1/3 XIII–XVIII, annular XV–XVIII but only dorsally in XIII–XIV.

Septa 5/6–11/12 muscular, remaining septa thin; 12/13 extremely so, partly absorbed into ovarian chambers; 13/14 also extremely thin, wrapped closely around posterior side of calciferous glands. Alimentary canal lacking esophageal gizzards; intestinal muscular rings in posterior halves of XIX–XXIII (5); paired calciferous glands in XIII, reniform with internal irregular lamellar structure; blood supply to glands consists of a portal circulation with afferent and efferent connections to the dorsal vessel; esophagus valvular in XV, intestinal origin XVI; intestinal gizzards in XIX–XXIII; typhlosole vestigial originating in XXVII. Paired vesiculate holonephridia in all segments; nephridia of XIII partly enclosed in ovarian chambers, partly on body wall; nephrostome protruding into XII from the ovarian chambers.

Vascular system with ventral trunk, single dorsal trunk, these connected by lateral trunks in VI–IX, lateroesophageal hearts in X, XI Supra-esophageal vessel Y-shaped to hearts in X, XI. Dorsal vessel in XIII has short connection to anterior face of each calciferous gland; in XIV a pair of longer valved branches to posterior face of each calciferous gland. Single sub-esophageal glands in IX, X, XI; the latter two with small blood vessel from the free end to an extra-esophageal blood vessel; all three joining ventral esophagus near the posterior of their respective segments. Internal structure of the subesophageal glands consists of many parallel blood vessels running the length of the gland; interspersed regularly within the blood vessels are many small tubes of light yellow appearance, but not containing calcium carbonate.

Female reproductive system consists of perispermathecal sinus composed of a single duct to the outside, which bifurcates and rejoins around the esophagus to make a ring, on dorsal edge of which a single tubular extension runs back through several segments; below the esophagus the duct first (ectally) branches laterally to paired ovarian chambers containing partial nephridia; slightly entally branches to ovisacs from which lead oviducts to the ovarian pores in XIV. Within the duct and the left side of the perispermathecal sinus is a muscular tube extending as high as the dorsal side of the esophagus.

Male sexual system holandric, testes, funnels in long tubular or banana-shaped sacs on the anterior faces of septa 10/11 and 11/12, from dorsal ends of which a duct passes through to a funnel-like structure in the seminal vesicles of XI, XII respectively. Within the testes sacs a tightly zig-zag folded tubular lumen with dense iridescent material, probably sperm cells. The ventral end of each testes sac passes through its respective septum to form the vas deferens; these remain separate on the body wall until just before reaching the euprostates in XVIII. Seminal vesicles small sacs high on the posterior faces of 10/11, 11/12. Euprostates only slightly muscular, more glandular in appearance with thick glandular wall and narrow undulating lumen; wall thickness diminishes ectally and undergoes a transition to densely muscular as it nears body wall; no penes present in terminal portion of prostatic duct; vasa deferentia joined together near the euprostate travel along the outer surface but embedded in it, to the ental end, at which point they enter the euprostate wall.

Remarks. Hyperiodrilus africanus and two species of the related genus Legonea Clausen, 1963 have highly variable seminal groove patterns ( Sims 1965; Zicsi & Csuzdi 1986). In light of this and the nearly identical internal anatomy, we are placing all specimens in one species. There were minor differences among specimens in the setal spacing but nothing consistent, and there are only 4 specimens in the collection. Beddard (1891) is inconsistent on the number of gizzards (5 or 6; XVIII–XXII or XXIII) in both text and illustrations, but Clausen (1967) concluded that the species has five gizzards in contrast to the opinion of Sims (1965) that there are 7 (XVI–XXII). Unfortunately the post-1891 records of the species do not give details on the locations of the gizzards. From Beddard’s (1891) figures 47 and 52, it is clear that the first gizzard is in XVIII, but we note that keeping track of segment number in this part of our worms was difficult. Therefore we cannot be certain that Beddard was correct, but we took pains to ensure that we are. Clausen (1967) believed that the gizzard number (and location?) is very stable and reliable within Hyperiodrilus , and had material with four gizzards that she was tempted to describe as new, but did not. The Gamba material has intestinal gizzards in XIX–XXIII and the spermathecal pore in XIII. If this turns out to be distinct from Hyperiodrilus africanus , then there may be justification to designate the Gamba population as representing a new subspecies. For this reason, and to avoid creating another record lacking anatomical data, we have given a full description of the material.

Hyperiodrilus africanus appears to be a widely distributed species, probably by the agency of human activity, such as transport of plants for horticultural or agricultural purposes ( Zicsi & Csuzdi 1986). Its presence at the Vembo area in Gamba, where we found many introduced species, is probably artificial.