Righiodrilus cusiani, Celis & Feijoo & Rangel-Ch, 2018

Celis, Liliana V., Feijoo, Alexander & Rangel-Ch, Orlando, 2018, Two new earthworm species (Oligochaeta: Annelida) of the Orinoquia region of Colombia, Zootaxa 4496 (1), pp. 440-447 : 441-445

Righiodrilus cusiani , sp. nov.

( Figure 1A,B , Table 1)

Material examined. Holotype: LVCelis192, clitellate specimen; Colombia, Department of Casanare, Aguazul (5°00'51.3'' N; 72°22'37.5' W), 200 m asl; L.V. Celis, 26 January 2015. Paratypes: LVCelis191, 9 specimens (7 adults, 2 juveniles); Colombia, Department of Casanare, Aguazul, 200 m asl; L.V. Celis, 26 January 2015.

Description. Body cylindrical, without pigment. Body dimensions, holotype: length 70 mm, diameter 2.1 mm in preclitellar region, 2.0 mm at clitellum, 1.9 mm in postclitellar region (segment xl), 180 segments; paratypes: length 50.7–80 mm, diameter 1.8–2.5 mm, 177–188 segments. Setae visible from segment iii; closely paired, 8 per segment, in two ventro-lateral and two latero-dorsal rows. Setae slightly sigmoid without node. Genital setae not found. Distance between setae in mid-body region (segments xl–l) aa: ab: bc: cd: dd = 24: 1.0: 4.0: 1.0: 31 (holotype). Clitellum saddle-shaped in segments 1/2 xvi –1/2 xxiii, xxiii; tubercula pubertatis in 1/4 xviii–xxi ( Fig. 1A ). Male pores at 19/20, female pores in segment xiv. Spermathecal pores visible in 8/9 and 9/ 10 in line with setae ab. Nephridiopores above setae b and visible from intersegment v.

Internal anatomy. Septa 7/8–10/11 thick and muscularized. Gizzard ovoid, in segment vi. One pair of extramural, pyriform calciferous glands with tubular structure emerging from region of esophagus of segment xi and extending to segment xvi, xvii, glandular part in segments xi, xii, xiii membranous part in segments, xiv, xv, xvi, xvii. Transition of esophagus-intestine in segment 13/14. Typhlosole simple, from intersegment 18/19, occupying 1/6 of gut diameter. Caeca absent. Three pairs of lateral hearts in segments vii, viii and ix, and two pairs of "intestinal" hearts in segments x and xi. One pair of holonephridia per segment. Male funnels in testicular sac in segment xi and connected to deferent ducts. One pair of seminal vesicles from segment xii, extending backwards to segments xxiv, xxv or xxvi. Male ducts run along the body wall down to 19/20. Ovaries in segment xiii. Two pairs of spermathecae in intersegments 8/9, 9/10; anterior spermathecae with long duct and rounded ampulla, posterior spermatheca with rounded and voluminous ampulla; it is more voluminous than first ( Fig. 1B ).

Etymology. The species is named after the Cusiana River in the Department of Casanare, Colombia.

TABLE 2. Comparison of species of the genus Andiodrilus with similar species (saddle-shaped clitellum, hearts in x–xiii)

Habitat characteristics. Righiodrilus cusiani sp. nov. was collected in the alluvial plain of Aguazul, at the Orinoquian region of Colombia. Plant formations include several grassland types growing on no flooded (unflooded) areas which are dominated by Andropogon bicornis and Steinchisma laxa and Axonopus purpusii and Trachypogon spicatus .

Comments. Righiodrilus cusiani sp. nov. is close to R. arapaco ( Righi, 1982) in the position of the clitellum and tubercles, and to R. mairaro ( Righi, 1982) in the position of the male pores. Righiodrilus cusiani sp. nov. is close to R. arapaco in the position of the clitellum (1/2 xvi– 1/2 xxiii, xxiii vs. 1/2 xvi –1/2 xxii in R. arapaco ) but differs in the extension of the tubercula pubertatis (3 1/4 segments vs. 2 in R. arapaco ) the position of the male pores (19/20 vs. 18/ 19 in R. arapaco ) and in the shape of the spermathecae (spermathecae with long duct and rounded ampulla vs. spermathecae pyriform and without distinction between duct and ampulla in R. arapaco ). The new species has the same position of the male pores as R. mairaro (19/20), but differs in the extension of the tubercula pubertatis (3 1/4 segments vs. 2 1/ 3 in R. mairaro ), the extension of the seminal vesicles (xxiv, xxv or xxvi vs. xxiv–xxxvi in R. mairaro ), the position of the clitellum (1/2 xvi– 1/2 xxiii, xxiii vs. xiv, xv–xxi in R. mairaro ), the position the spermathecae pores (8/9, 9/10 vs. 7/8, 8/ 9 in R. mairaro ) and in the shape of the spermathecae (anterior spermathecae with long duct and rounded ampulla vs. anterior spermathecae without distinction between duct and ampulla) (Table 2).

Figures

FIGURE 1. Righiodrilus cusiani (A,B) and Andiodrilus cravijae spp. nov. (C–I). Righiodrilus cusiani sp. nov., holotype. A. Ventral view. B. Spermathecae. Andiodrilus cravijae sp. nov., holotype. C. Common seta. D. Genital seta. E. Ventral view. F. Internal dorsal view (Gi, Gizzard; Cg, calciferous glands; Ts, Testis sac; Sv, seminal vesicle; Lh, Lateral heart; Ih. Intestinal heart). G. Calciferous gland. H. Nephridium. I. Spermathecae.