Lavellodrilus notosetosus, Fragoso, Carlos & Rojas, Patricia, 2016

Fragoso, Carlos & Rojas, Patricia, 2016, Lavellodrilus notosetosus sp. nov. (Annelida, Crassiclitellata, Acanthodrilidae): a new Mexican earthworm with uncommon characters, revealed by a preliminary revision of subfamily Acanthodrilinae, Zootaxa 4154 (2), pp. 101-138 : 104-106

Lavellodrilus notosetosus sp. nov.

( Figures 1 , 2 , 3 )

Localities and material. Mexico, Chiapas, Chajul village , municipality of Marques de Comillas : 1) Type locality (holotype and paratypes), in front of town and crossing the river Lacantun, 2 km NW inside Montes Azules Biosphere Reserve, tropical rain forest over alluvial soils at 20–40 cm depth, 16°07’24”N, 90°56’24”W, 180 m asl, five non-clitellated semi-adults 12/28/1982, and one juvenil 12/29/1982, C. Fragoso; three juveniles , 06/07/1982, P. Lavelle; six juveniles and one non-clitellated semi-adult 06/05/1982, P. Lavelle; three juveniles 07/11/1982, C. Fragoso; one juvenile 11/14/1981, P. Lavelle and C. Fragoso; 2) 3 km SW from town, very near to the river Lacantun in a recently deforested parcel over alluvial soils, within soil . 16°06’15”N, 90°57’00”W, 200 m asl, two juveniles 12/12/1984, C. Fragoso; 3) 2 km SE from town, disturbed tropical rain forest with seedlings of cocoa over ferrallitic soils at 30–40 cm depth. 16°06’42”N, 90°54’48”W, 200 m asl, one juvenile 08/28/1984, C. Fragoso.

Holotype. Fragmented non-clitellated semi-adult with genital marks (GM), penial (PS) and genital setae (GS) collected in locality 1, 12/28/1982: IEOL 3109–1.

Paratypes. All are dissected non-clitellated worms from locality 1: two entire semi-adults with GM, PS and GS, 12/28/1982: IEOL 3109–2, IEOL–3108; three fragmented semi-adults with GM, PS and GS, 12/28/1982: IEOL 3123; 06/05/1982: IEOL 3117; 06/07/1982: IEOL 3111; one fragmented juvenile with poorly developed GM, PS and GS, 07/11/1982: IEOL 3110–2; one fragmented semi-adult lacking the first 15 segments, with GM and PS, 12/28/1982: IEOL 3108–2; two entire juveniles without GM, PS and GS, 12/29/1982: IEOL–3127; 08/28/ 1982: IEOL 3120.

Description. External. Length at least 135 mm in a fragmented and non-clitellated individual, holotype 111 mm (fragmented). Width, between segments 25–30: 1.22–1.55 mm (mean= 1.36, n= 9; Holotype 1.33 mm). Number of segments 201–271 (mean= 249, n= 4). Anterior segments almost square ( Fig. 1 A,F); after segment 20 they become more rectangular; in the posterior region of some individuals, segments are narrow and apparently regenerated. Pigment absent. Prostomium prolobous or slightly epilobous, retracted in the majority of individuals. Secondary furrows one presetal in 3 and 4; one presetal and one postsetal in 5; two/three presetal and two/three postsetal in 6–22; behind segment 22, several presetal and postsetal annulations. Setae eight per segment, visible from 2; widely paired throughout, ab always ventral, cd lateral in the first segments and gradually moving to dorsum from 13, after segment 20 completely dorsal ( Fig. 1 E). Size of setae cd gradually increasing in 2–6, and then decreasing; in segments 5, 6,11,12,13 with internal replacements; from segment 40 backwards, setae d larger than c ( Fig. 1 E). Setal formula (averages, n=6) (aa:ab:bc:cd:dd): 10: 2.6:1:4.2:1.7:8.6 and 1.2 dd =1/2 C; 30: 6.1:1:12.5:2.5:4.8 and 3.3 dd =1/2 C; ten segments before anus: 6.7:1:11.4:2.1:4.9 and 3.1 dd =1/2 C. Setae ab of segment 12 modified as genital setae ( Fig. 2 A), within follicles attached to lateral parietes and with several extra setae ( Fig. 3 A). They are slightly curved, length 1.26–1.35 mm, with ornamentation covering 63% of distal surface and consisting of quincuaxial crevices that become smaller towards distal region; apex pointed ( Fig. 2 B). Thin and large immature paired penial setae (a and b) in 17 and 19. In the holotype, the largest recovered complete seta of 17 b measured 1.83 mm length and 9.6 µm width; the setae was not straight, with a curvature of nearly 180° in the last distal third ( Fig. 2 C). Due to its immature stage, ornamentation was not fully developed, limited to the last distal third and characterized by smooth undulations that become scarce serrations near to the slightly arrowshaped apex ( Fig. 2 D). Mature penial setae probably spiral-shaped in the distal end. Setae a and b of 18 not visible. Clitellum not developed in any of the examined individuals. Dorsal pores present all along the body, first functional open pore in 13/14 (N= 11 ind.). Spermathecal pores paired and mesial in 7/8 and 8/9, within ovoid papilla located in AA ( Fig. 1 A,F). Female pores in 14, presetal, mesial and median to a ( Fig. 1 B). Two pairs of mesial prostatic pores in 17 and 19, joined by seminal grooves which in segment 18 run in AB ( Fig. 1 A,C). Male pores not seen, probably within seminal grooves and opening somewhere in 18. Genital marks unpaired, mid-ventral intersegmental papillae located in 19/20 (extending in AA), 20/21 (BB), 21/22 (AA or BB) and 22/23 (mesial); relative size: 20/21≈21/22>19/20>22/23 ( Fig. 1 A,C,F). Two further genital marks: an irregularly butterfly-like swelling in segment 12 ( Fig. 1 A,D,F), incipient in several individuals, better differentiated in holotype and some paratypes, and a semicircular smooth mesial papilla in 16/17, with a straight posterior end ( Fig. 1 A,C,F).

Internal. Septum 5/6 very thin and membranous; septa 12/13 and 13/14 slightly muscular, 6/7–11/12 muscular; septa 6/7–13/14 funnel-shaped and imbricated ( Fig. 3 A), those of 6/7–11/12 joined by 4–6 dorsal and lateral connective tissue fibers. Insertions of septa 6/7–13/14 not corresponding with external intersegments, being attached slightly anteriorly ( Fig. 3 A). One small cylindrical gizzard in 5, completely occluded by septum 6/7. The thin nature of septum 5/6 often gives the erroneous impression that gizzard occurs in 6. Gizzard dimensions (length, width, and wall thickness): 0.59–0.88 mm, 0.32–0.58 mm, and 46–126 µm. Esophagus in 7–12 tubular, without dilatations or internal lamellae and with a pebbly internal wall. In 13–18 esophagus vascularized, with a thick wall and/or internal lamellae and with intra-parietal ventral paired vessels; in this region some segments enlarged (varying according to individuals) in some cases resembling lateral pouches. Intestine starting in 19/20 (7 ind.) ( Fig. 3 A), 18/19 (2 ind.), 17/18 (1 ind.). Dorsal typhlosole starting in 20, 21 or 22, laminar, small, reaching maximal size after 2–3 segments, ending in 98, 103, 125, 127, with a gradual decrease in size some segments before its end. Dorso-lateral typhlosoles covering ten to thirteen segments of region 20–34, at both sides of main typhlosole. Single dorsal vessel visible throughout. Supra-esophageal vessel clearly visible in segments 11–14; in some individuals visible also in segments 9 and 10. Lateral hearts in 9 and 10; latero-esophageal hearts in 11, 12 and 13. Ventral vessel present. Extra parietal lateral-ventral vessels observed in one individual, in segments 16–22, anastomosing with body wall; in another individual, a pair of infra-parietal esophageal vessels observed in segments 9 and 10. Holoic without vesicles. The exonefric, apparently stomate holonephridia are septal from 5/6 to 19/20 (in the anterior face of the respective septum) and parietal from segment 20 backwards ( Fig. 3 A). Nephrostomes and nephropores not seen; in anterior segments nephropores probably located in mid- BC, presetal, and close to the intersegment ( Fig. 3 A).

Holandric. Testes and male funnels in 10 and 11, not completely developed; funnels without iridescence. Undulate male gonoduct double, superficial and running over the body wall of segments 13–16 in AB; in 17 curved mesially, entering body wall in 17/18. Two pairs of sub-esophageal immature seminal vesicles in 11 and 12. Two pairs of immature and slightly coiled tubular prostates in 17 and 19 ( Fig. 3 B), largest in 17; glandular part at least 3–4 times larger than the muscular region. Penial setae follicles fixed to lateral walls and extending two, three segments backwards ( Fig. 3 B). Paired ovaries and female funnels in 13 (observed only in the holotype). Ovaries fixed to floor, flat and with a distal row of developing eggs. Two pairs of not fully developed spermathecae in 8 and 9, the posterior one being larger; diverticulum lateral, emerging from the anterior part of the duct and at least half the size of ampulla ( Fig. 3 C). The larger, still immature spermatheca sized 1.26 mm (Paratype IEOL 3111) ( Fig. 3 D).

Etymology. The name of the species refers to the dorsal position of setae cd in the majority of segments.

Remarks. Lavellodrilus notosetous sp.nov. is clearly separated from the other species of the genus by the following characters: beginning of intestine (18, 19, 20 vs 14 or 15), position of setae cd after segment 25 (dorsal v s lateral), location of last heart (13 vs 12), position of genital setae (12 vs absent or in 8 and/or 9) and type of penial setae. This species has previously been referred to as “Gen. n. 3 ( Fragoso & Lavelle 1987, Fragoso 1992) and Lavellodrilus sp. nov. 9 ( Fragoso 2001, 2007). Fragoso and Lavelle (1987) classified it as a geophagous hydrophilic species that inhabits alluvial soils within tropical rain forests, below 20 cm of soil depth and close to small streams. The species was recognized as new several years ago; however we delayed the publication hoping to obtain mature, clitellated adults. At first it was considered as a new, different genus; later on we realized that it presented the mesial pores and several other common characters that deserve its inclusion within Lavellodrilus. After more than 30 years, and considering that no new material was collected or received, we decided to publish it as a new species.

Figures

FIGURE 1. Lavellodrilus notosetosus sp. nov. External. A. Ventral view of anterior region (Holotype IEOL- 3109; scale 1 mm). B. Ventro-lateral view of female pores (Fp) (Paratype IEOL- 3123; scale 1 mm). C. Ventro-lateral view of the genital zone showing genital papillae (Gp) and prostatic pores (Pp) (Paratype IEOL- 3109 - 2; scale 1 mm). D. Ventro-lateral view of segment 12, showing the butterfly-like genital mark (Paratype IEOL- 3123; scale 1 mm). E. Transverse section in the middle part of the body, behind segment 40, showing somatic setae (a, b, c, d), dorsal vessel (Dv) and intestine (I) (fragment of an individual collected 06 / 05 / 1982; scale 1 unity = 0. 21 mm) F. Ventral view of anterior region (Paratype IEOL- 3109 - 2; scale 1 mm).

FIGURE 2. Lavellodrilus notosetosus sp. nov. Setae. A. Right genital setae a of segment 12 (Holotype IEOL- 3109; scale 400 µm). B. Apex of genital seta 12 b (Holotype; scale 10 µm). C. Right penial setae b of segment 17 (Holotype IEOL- 3109; scale 500 µm). D. Apex of penial seta 17 a (Paratype IEOL 3108 - 2; scale 20 µm).

FIGURE 3. Lavellodrilus notosetosus sp. nov. Internal. A. Dorsal view of segments 9 – 22; below septum 13 / 14, hearts, dorsal vessel and esophagus of segment 13 are diagrammatically shown (Paratype IEOL- 3127; scale 2 mm). ES = Esophagus, vascularized region, G = Genital setae within follicles, H = Heart, HP = Parietal holonephridium, I = Start of intestine, PS = Penial setae follicles, S = septa SS = Somatic setae cd. B. Prostatic glands and penial setae follicles of segments 17 and 19; the intestine and esophagus were removed to facilitate view; (Holotype IEOL- 3109; scale 1 mm). C = Nerve cord, M = Prostate muscular duct, PG = Prostate glandular region, PS = Penial setae follicles. C. Spermathecae of segment 9 in situ, dorsal view (Paratype IEOL- 3109 - 2; scale 500 µm). D. Extracted left spermatheca from segment 9, (Paratype IEOL- 3111; scale 500 µm). A = Spermathecal ampulla,). C = Nerve cord, DU = Spermathecal duct, DI = Spermathecal diverticle,