Arraia nelmae Hernandez-Garcia & James, 2018

Hernández-García, Luis Manuel, Burgos-Guerrero, Jesús Enrique, Rousseau, Guillaume Xavier & James, Samuel Wooster, 2018, Brasilisia n. gen. and Arraia n. gen., two new genera of Ocnerodrilidae (Annelida, Clitellata, Oligochaeta) from Eastern Amazonia, Brazil, Zootaxa 4496 (1), pp. 472-480 : 476

Arraia nelmae Hernandez-Garcia & James , n. sp.

( Figure 3A–F )

Holotype. MPEG.ANL 0 0 0 325 adult, Rosário , Maranhão, Brazil, homegarden, 02°49'S 44°08'W, 38 masl. 0 3 June 2014. Muñoz J.A. & Cardozo E.G. colls.

Paratypes. MPEG. ANL 0 0 0 326 three adults, same data as holotype, MPEG .ANL 0 0 0 327 one adult, 02°51'S 44°09'W, 14 masl. 0 2 June 2014. MPEG.ANL 0 0 0 328 one adult, old secondary forest 02°51'S, 44°09'W, 89 masl 31 May 2014. Muñoz J.A. & Rousseau G.X. colls.

Etymology. The species name is derived from Nelma Freitas, the landowner of the homegarden where the holotype was collected.

Description. Dimensions: Holotype 346 mm by 1.9 mm at segment X, 2.2 mm at clitellum, 1.8 mm at XXX, body cylindrical, segments 100. Paratypes 210–350 mm by 1.2–1.9 mm at segment X, 1.65–2.2 mm at clitellum, 1.5–1.8 mm at XXX, body cylindrical, segments 73–112. Setae closely paired throughout, ab beginning in II and cd beginning in III; setal formula aa:ab:bc:cd = 6:1:5:1 at X, 5:1:3.5:1 at XXX, DD> ½ circumference. Prostomium tanylobous; segments lacking secondary annulations. Unpigmented, dorsal pores absent, spermathecal pores within 8/9 approximately centered in b line; with tumid lips more than ab. Ovipores in XIV just behind 13/ 14 in b line; male pores in 16/17, near prostatic pores in a line. Prostatic pores at ends of grooves, along b line in XVII. Setae ab of XVII unmodified. Clitellum in XIV–XVIII, saddle-shaped to b line ( Fig. 3A ). Post clitellar common setae 170–190 µm in length, smooth and sigmoidal form. Genital setae 200–210 µm in length, excavation absent and slightly sigmoid ( Fig. 3B ).

Anterior septa 5/6–9/10 slightly muscular, in following segments decreasingly muscular until remaining all thin. Gizzard in VI; esophagus valvular in XII, intestinal origin in XIII; lacking typhlosole. Calciferous glands paired in IX, tubular type ( Fig. 3C,D ), each gland with a thin blood vessel from anterior end to extra-esophageal vessel, blood vessel from duct of gland to supra-esophageal vessel. Holonephric, first nephridia visible in segments XI–XIII. Post clitellar nephridia with one short loop open in a laminar bladder ( Fig. 3E ). Vascular system with ventral trunk, single dorsal trunk V–IX, dorsal vessel single; lateral vessels in V–IX, latero-esophageal hearts X–XI.

One pair of ovaries and female funnels in XIII. One pair of small adiverticulate spermathecae in segment IX, cylindrical shape. Spermathecal ducts as wide as ampulla, open to septa 8/ 9 in b line ( Fig. 3F ). Male sexual system holandric, testes and funnels in X, XI, within sacs, vas deferens superficial on internal body wall from 9/10–10/11, to body wall in XVII where it runs through b line ending just in 16/17 near to prostatic pore; seminal vesicles occupying segments IX–XII, covering the esophagus. Tubular prostates in XVII. Four individuals with tubular prostates extended to anterior, ending in the pharynx region. Glandular diameter of prostates 100 µm, duct diameter was 60 µm; prostatic ducts 175–200 µm in length (2 to 3 segments long), muscular, enter in XVII in equatorial line at b line.

Remarks. This new species is the first described from its genus. We determined it to be new based on the summary of genus characters implicit in the key of Fragoso & Rojas (2009). Arraia n. gen. is similar to Xibaro genus ( Righi 1981) by the gizzard in segment VI, calciferous glands paired in IX, male and female reproductive system holandric and metagynous, respectively, and dorsal pores absent. The principal difference between the new genus and Xibaro is the number of gizzards: while Arraia n. gen. has only one gizzard in VI, Xibaro has two gizzards, one in VI and another in VII. The male pores for Arraia n. gen. are in 16/17 while in Xibaro they are in XVIII. There are two pairs of prostates in segments XVII and XIX in Xibaro , while in Arraia n. gen. there is only one pair in XVII.

Figures

FIGURE 3. Arraia nelmae n. gen. A. Ventral view of anterior body, with clitellar region. B. Genital seta of a line of segment XVI. C. Dorsal view of left calciferous gland of IX. D. Transversal cut of left calciferous gland of IX. E. Dorsal view of left post-clitellar nephridium. G. Dorsal view of right spermatheca of IX.