Eiseniona gerardoi Diaz Cosin

Diaz Cosin, Dario J., Novo, Marta, Fernandez, Rosa, Fernandez Marchan, Daniel & Gutierrez, Monica, 2014, A new earthworm species within a controversial genus: Eiseniona gerardoi sp. n. (Annelida, Lumbricidae) - description based on morphological and molecular data, ZooKeys 399, pp. 71-87 : 76-78

Eiseniona gerardoi Diaz Cosin sp. n.

Material examined.

Holotype. Adult (Catalog # UCMLT 60000), 40°13'38.80"N, 6°18'36.04"W ("spanish dehesa" mediterranean grazed open woodlands of Quercus ilex ), near El Bronco ( Cáceres, Spain), leg. G. Moreno, E. Juárez, April 2010.

Paratypes. 18 specimens (Catalog # UCMLT 60001 to 60018), leg G. Moreno, E. Juárez, April 2010.

Morphological description.

External morphology (Figures 2, 3). Length of mature specimens: 21-40 mm, x: 28 mm, SD: 5.6 mm, holotype: 31 mm. Diameter: clitellar x: 2.5 mm, SD: 0.4 mm, holotype: 2.5 mm, postclitellar x: 1.8 mm, SD: 0.2 mm, holotype: 1.7 mm. Body cylindrical in the anterior part, wider at clitellum and trapezoidal or rectangular in postclitellar region, with chaetae in the corners. Number of segments: 89 to 124, x: 109.5, SD: 10.7, holotype: 117. Weight (fixed specimens): 38 to 64 mg, x: 52 mg, SD: 13 mg, holotype 62 mg.

Colour: When alive, the anterior part is red-brownish showing noticeable antero-posterior and dorso-ventral gradients. Cream-coloured or whitish clitellum. After a long period within alcohol the red pigment is gradually lost and transformed into brown of different intensities (Figure 2).

Prostomium epilobic ± 1/3. No longitudinal lines are noticeable in segments 1 and 2. First dorsal pore in (3/4) 4/5. Nephridial pores inconspicuous in a row slightly above b. Spermathecal pores at intersegments 9/10 and 10/11, at the level of chaetae cd (Figure 3).

Male pores as vertical grooves in the segment 15 between chaetae b and c showing small porophores with whitish areolae shape. Female pores in 14 slightly above b. Chaetae paired, interchaetal ratio at segment 40, aa: 16, ab: 1.4, bc: 7, cd: 1, dd: 24. Chaetae are simple with a wider base and a sharp and bent distal end. (Figure 4).

Clitellum white or cream-coloured, saddle-shaped extending over 22,23-29,30, in the holotype 1/n 22, 23-29. When well developed it invades the ventral area and the intersegmental lines are hard to distinguish. Tubercula pubertatis extended as a belt in 23-(27)28,29, in the holotype in 23-29. Occasionally they appear folded or wrinkled. No noticeable papillae are present in any of the specimens.

Internal anatomy. Slightly thickened anterior septa. Last pair of oesophageal hearts in 11. Morren’s glands with small diverticula in 10 and little lamellae in 11 and 12. Crop in 15,16, gizzard in (17)18,19. First section of the intestine is not dilated. Simple typhlosole pleated, which begins in 20, 21 and ends near the anus leaving only 10-15 atyphlosolate segments.

Fraying testes and iridescent and very large seminal funnels in 10 and 11. Three pairs of seminal vesicles in 9, 11 and 12. The last pair is very large pushing back the septum 12/13. Large ovaries and female funnels in 13, ovarian receptacles (ovisacs) in 14. Two pairs of very large and iridescent spermathecae in segments 10 and 11.

In the posterior region of the body the nephridia are much enlarged, the nephridial bladders are curved and J-shaped with curved section 1/3 of total length. (Figure 5).

An important characteristic is the presence of dense white glands on top of the dorsal vessel initially around segment 20 and externally visible as a whitish line extending to the end of the body. (Figure 6).

Distribution.

Known only from its type locality.

Etymology.

The species is dedicated to Prof. Gerardo Moreno from Centro Universitario de Plasencia, Universidad de Extremadura, Spain. He is the PI for the Bio-Bio program in Spain and collected the specimens described in this paper.

Molecular characters.

Sequences of the used genes have been deposited in GenBank (see Table 1). According to Drs. Pérez Losada and Domínguez (pers. comm.), the 16S and 28S sequences of Eiseniona gerardoi clustered with the two species classified as Eiseniona , Eiseniona albolineata and Eiseniona oliveirae .

The phylogenetic tree presented here, based on the COI gene and including some of the available species in GenBank (Figure 7), shows that Eiseniona gerardoi specimens form a highly supported group (1.00 posterior probability, 0.99 bootstrap) with Eiseniona albolineata . The two species share the presence of whitish glands on top of the dorsal vessel. COI genetic divergence (uncorrected p-distances) between Eiseniona albolineata and Eiseniona gerardoi is 14.09%, and the intraspecific variability of the latter is 2.81% showing a very close relationship.

Habitat and ecological characters.

All the soils from sampling sites have been developed on slates and are sandy-loams. Precipitation corresponds to the typical values of intermediate semi-humid Spain. The associated species Allolobophora molleri is always present and this species is bound to terrains that are flooded during several months per year. Additionally, the presence of plants typical from wetlands, such as Eleocharis palustris , Pulicaria paludosa or Juncus bufonius indicates that in these sites there is enough humidity during most of the year, which supports hygrophile communities. Nevertheless they could be desiccated in the summer, which would force the earthworms to undergo aestivation in order to survive to these dry periods, resuming activity when humidity is restored. All these details are compatible with the diagnosis of the genus by Omodeo (1956) as he highlighted the semiaquatic characteristics of Eiseniona .