Howascolex farafangana, Csuzdi, Csaba, Razafindrakoto, Malalatiana & Hong, Yong, 2016

Csuzdi, Csaba, Razafindrakoto, Malalatiana & Hong, Yong, 2016, The second species of the endemic Malagasy earthworm genus Howascolex Michaelsen, 1901; Howascolexfarafangana sp. n. (Clitellata, Megadrili), African Invertebrates 57 (2), pp. 83-91 : 86-87

Taxon classification Animalia Haplotaxida Acanthodrilidae

Howascolex farafangana sp. n. Figs 2-6

Etymology.

Noon in apposition, refers to the type locality; Farafangana district, SE Madagascar.

Description.

External: Length of the Holotype 155 mm, width (postclitellar) 7 mm. Segments No. 205. Paratypes 142-150 mm in length and 6-7 mm in diameter, segment No. 186-228. Color greyish, pigmentation absent. Prostomium schizolobous, dorsal pores from 9/10. Segments from 3-12 bi- or triannulate, after clitellum with three or four ringlets. Setae visible from segment 2, eight per segment in closely paired regular rows. Setal formula after clitellum aa:ab:bc:cd:dd = 9.2:1.4:10:1:40 (Fig. 2). Setae a and b of 8, 9 modified to genital setae, of 17, 19 modified to penial setae. Spermathecal pores paired, presetal small slits on segment 8, 9 between a–b. Clitellum saddle-shaped on 13-19. Female pores in 14, presetal and slightly lateral to b. Two pairs of prostatic pores in 17 and 19 just at the base of seta b, joined by slightly convex seminal grooves, running outside b. Male pores minute in 18, within the seminal grooves. Genital marks unpaired as 2-3 mid-ventral, intra and intersegmental papillar lines located in the region 19-22 and paired group of small postsetal papillae on 8, 9, 10, 12 in setal lines a–b (Fig. 3)

Internal: First septum visible 6/7, septa 8/9, 12/13-13/14 thickened, 9/10-11/12 strongly muscular. One large oesophageal gizzard in 5 or 6, extending up to segment 7. Dorsal vessel single throughout, last pair of hearts in 13. Excretory system with 2-3 coiled (interconnected?) exoic and stomate nephridial tufts per side before clitellum. After clitellum their number increases to 5-6 discrete biramous meronephridia and a ventral megameronephridium per side. Large intramural calciferous gland present in segment 16 sometimes bulging into segment 17 as well. Intestine begins in 20 bearing medium-sized lamellar typhlosole from 23. Lateral typhlosoles lacking.

Holandric. Two pairs of testes in 10, 11. Male funnels iridescent and plicated, testis sacs missing. Two pairs of seminal vesicles in 11 and 12, attached respectively to septa 10/11 and 11/12. One pair of moderate size ovaries in 13. Two pairs of tubular prostates of similar size in 17 and 19, highly coiled and confined to their own segment. Penial setae 3.5 mm in length and 0.025 mm in diameter. The ectal third bent, tip slightly lanceolate, ornamentation fine transversal serrations (Fig. 4).

Two pairs of spermathecae opening segmentally on 8 and 9. Ampulla slightly elongate, oval, duct short. Diverticulum front-facing, acinous, joins to the duct just above the spermathecal pore (Fig. 5). Genital setae almost straight, 1.8 mm long, and 0.035 mm in diameter. Tip lanceolate, ornamentation dense sharp scales (Fig. 6).

Holotype.

HNHM/AF5664. Madagascar, Vatovavy Fito Vinany, Farafangana, Tsararafa, Anrazomafaitsa. 22°43'35"S, 47°47'38"E, 28 m asl. Legit: Y. Hong & M. Razafindrakoto 20. 02. 2015.

Paratypes.

HNHM/AF5665, 3 ex. Locality and date same as that of the Holotype. HNHM AF/5666, 2 ex. Madagascar, Vatovavy Fito Vinany, Farafangana, Tsararafa, Anrazomafaitsa 22°38'42"S, 047°50'4"E, 63 m asl. Legit: Y. Hong & M. Razafind-rakoto 18. 02. 2015.

Remarks.

This second species of Howascolex differs from the generotype by its larger size, the segmental spermathecal pores and in the presence of genital setae. The presence of a moderately sized typhlosole is also a difference, however the original description is erroneous reporting complete lack of typhlosole in Howascolex madagascariensis . Opening the intestine just after the prostatic segments a small twine-like typhlosole can be observed running along the dorsal surface of the intestine.