Lacandodrilus paludosus Fragoso & Rojas 2023

Jamieson, Barrie G. M. & Fragoso, Carlos, 2024, A monograph of the Oligochaete family Alluroididae, Zootaxa 5529 (3), pp. 401-435 : 426-428

Lacandodrilus paludosus Fragoso & Rojas 2023

Lacandodrilus paludosus Fragoso & Rojas 2023 , 5255 (1), 136–156.

Maximal length 58 mm. width, midbody 0.64 mm; number of segments 248. Secondary annulation one pre– and one post–setal throughout the body. Pigmentless. Prostomium prolobious. Setae eight per segment, present from II; closely paired throughout. Setae of preclitellar segments conspicuous and with replacements. Setae a and b of preclitellar segments 130–150 µm long, almost straight, with a slight nodulus close to the basal end; without ornamentation. Setae ab of XI and XII larger, replacement setae 64 and 93 µm long; seta c (112 µm) and d smaller than seta a and b. Behind clitellum all setae similar (slightly curved and without ornamentation) measuring 105–117 µm. Setae aa:ab:bc:cd:dd at X: 3.7:1:4.7:0.9:9.2 and 0.54 dd; dd =½C (cd dorsal); at XXX: 5.7:1:5.3:1:14.2 and 0.7 dd =½C (cd slightly dorsal); ten segments before anus: 2.9:1:2.4:1:14.4 and 1.2 dd =½C (cd ventral). Clitellum annular, from ½XII–½XVI, very thin. Dorsal pores absent. Spermathecal pores not visible. Female pores in XIV, presetal in AB. Nephridial pores not visible. Lateral lines (latero–muscular grooves) in BC close to C, from II or III to XIV, XVI or XX and more posterior segments; in one individual in CD.

Septa all thin and membranous. Paired septal glands in V, VI, VII, VIII and IX (in X incipient), attached to corresponding posterior septum, mixed with lateral vascular commissures. Gizzard, caeca and typhlosole absent. Oesophagus moniliform, with no distinct transition to intestine. Dorsal vessel single; sometimes increasing from XIV posteriad. Vascular commissures long and contorted in segments V?, VI–XI; embedded in septal glands. Ventral vessel present. Ventral holonephridia from XI backwards; covered by a granular peritoneal layer giving them an ovoid, flat appearance; this ovoid portion floating in the coelom, and not attached to septa. Nephridia gradually increasing in size and from XV attaining maximal size; exonephric (opening in ab) and probably open (stomate). Holandric; iridescent male funnels in X and XI; those of XI the larger; testes not seen. Both funnels enclosed in seminal vesicles. Male gonoduct coming from male funnels of X entering the body wall in XI; a second gonoduct coming from funnels of XI entering the body wall in XII. Both male ducts intraparietal over XI, XII and 3/4 of XIII (deduced from the externally observed, undulating cream band). Accordingly, male pore deduced to be in XIII, postsetal and in BC. One pair of sausage–shaped vesicles in XI; projecting in posterior direction from XII until segments XVIII or XX and running dorsolateral of the digestive tract, completely covering it. In X another pair of vesicles that also contain male funnels that run in anterior direction before turning over 180° and which, apparently, are limited to XII. Two pairs of lobulate, rosette–shaped glands internally on the ventral body wall XIII and XIV, the anterior the larger; composed of several short lobules, deduced to be prostatic glands. No tubular, atrium–like glands present. Large ovaries in XIII projecting from the ventral portion of 12/13 at AB and extending over the entire segment. Female funnels on the ventral wall of XIII very close to 13/14, in AB, and with a duct opening in XIV before setae ab. Septum 13/14 apparently modified as dorsolateral paired ovisacs that contain the corresponding seminal vesicles of XII and extending backwards until XVIII or XX. One pair of adiverticulate spermathecae in X opening ventrally in 9/10, at AB, the duct turned 180° to connect with a sausage–shaped ampulla. Total length of spermathecae 580 µm, 370 µm the ampulla, and 210 µm the duct.

Distribution. Mexico, Chiapas, Lacandon tropical rain forest in semi–inundated gley soils at 30–40 cm depth.

Remarks. This species was considered as gen.nov.sp.nov.4, but not named, by Fragoso & Lavelle (1987). Fragoso and Rojas (2033) suggest that future morphological and molecular evidence might render Lacandodrilus the type of a new family within the order Alluroidida . The absence of normal atria and presence of two pairs of prostates not associated with the male pores lend some support to this proposition.