Grania brasiliensis Prantoni & Wit & Erséus 2016, SP. NOV.

FIGURE 1

Holotype

ZUEC CLI 04, individual CE20734, whole-mounted, sexually mature specimen, with some segments amputated, from Ponta do Poço, Paranaguá Bay, Paraná State, southern coast of Brazil, 25°32′54″S, 48°23′18″W, estuarine subtidal, 7 m depth, medium to coarse sand with some mud, and lots of shell and cirriped fragments. Collected by A. L. Prantoni, 19 August 2013. COI barcode sequence, GenBank acc. no KT428110; for other sequence data, see Table 1.

Etymology

Named for Brazil.

Paratypes

ZUEC CLI 05 – CLI 07, three whole-mounted adult mature specimens, one from the type locality and two from the rocky promontory of the Ponta do Baleeiro beach, São Sebastião, São Paulo State, south-east coast of Brazil, 23°49′41″S, 45°25′23″W, lower intertidal pond, gravel and coarse sand with shell fragments, A. L. Prantoni, 28 October 2012. Paratypes not barcoded.

Description

Holotype> 5.71 mm long,> 38 segments (posterior end used for genetic analyses), 0.18 mm wide at segment III, 0.15 mm wide at segment XII, and 0.12 mm wide at segment XXI. Paratypes (complete adults) 5.28– 13.7 mm (n = 3), 40–61 segments (n = 3), 0.12–0.14 mm wide at segment III, 0.13–0.15 mm wide at segment XII, 0.13–0.17 mm wide at segment XXI (n = 2; one paratype not suitable for width measurements). Prostomium small, rounded, 45–65 μm long, 39–81 μm wide (n = 4); epidermis not reduced at front tip, 7–16 μm thick. Ventral chaetae from segment IV, lateral chaetae from segment XVII (n = 2) or segment XVIII (n = 2). Chaetae (Fig. 1A) 35–60 μm long, shaft straight, 3.5–5.0 μm thick at midpoint, L-shaped, proximally bent into a short oblique foot, with low instep and receding heel. Chaetal index (Rota & Erséus, 2003) 3.61 ± 0.56 (n = 5). Epidermal gland cells inconspicuous. Clitellum (not well developed in the holotype) maximally 18 μm thick, extending over segment XII and anterior half of segment XIII, comprising more or less regular transverse rows of hyaline cells alternating with granular cells; hyaline cells more abundant than granular cells; both types of cell absent midventrally between male pores (Fig. 1C). Spermathecal pores paired, lateral, somewhat posterior to 4/5. Male pores ventrolateral in middle of segment XII. Female pores ventrolateral, just posterior to 12/13. Anus directed ventrad (paratypes).

Brain posteriorly indented. Head organ (sensu Rota & Erséus, 1996) absent. Pharyngeal glands in segments IV–VI; dorsal lobes present in segment IV (one pair), segment V (one pair), and in segment VI (one pair), ventral lobes present in segment IV (one pair), segment V (two pairs), and in segment VI (two pairs); glands not connected dorsally. Nephridia not observed. Chloragogen cells inconspicuous. Dorsal blood vessel arising in segment XIX or XX. Coelomocytes sparse, small, up to 11.5 μm long, irregularly oval or circular; cytoplasm with fine granulation around cell nucleus. Sperm sac extending into segments XIV– XVI. Egg sac extending into segments XVII–XXII. Sperm funnels very long, in segments XI–XII (paratype) or segments XI–XIV (holotype), 10–12 times longer than wide, directed posteriorly (n = 2) (Fig. 1D). Vasa deferentia 7 μm wide, coiled and reaching at least into segment XV. Penial apparatus type 1 (sensu Coates, 1984), with small, round bulb, 59 μm long, 62 μm wide (n = 1), or oval bulb, 69 μm long, 38 μm wide (n = 1); bulb glandular, surrounding a simple invaginated male pore; stylet absent (Fig. 1D). Midventral copulatory gland (in segment XIV) present. Spermathecae communicating with the oesophagus close to septum 5/6 through narrow ental ducts. Ectal ducts spindle-shaped, thick-walled, muscular, 67–79 μm long, 31–40 μm thick at midcourse, joining ampullar cavity through conspicuous deep conical intrusion. Ampullae 41–66 μm long, 36–59 μm wide; oval, ectally granulated (Fig. 1B). No glands at ectal pores of spermathecae. Sperm rings not observed in ampullae.

Remarks

The combination of the long sperm funnel, presence of a midventral copulatory gland in segment XIV, and the unusual clitellum, with hyaline cells more abundant than granular cells, may differentiate this new species from all other described species of Grania.

Grania brasiliensis sp. nov. appears to be similar to the Caribbean species G. americana, by the shape of the spermathecae, total length, and number of segments. In addition, the genetic analyses indicate that these two species are closely related (see Phylogenetic analyses). There are at least two obvious morphological differences, however: G. americana is distinguished from G. brasiliensis sp. nov. by its large glands at the spermathecal pores and the presence of a head organ.

Two species from the South Atlantic, sub-Antarctic island of South Georgia, i.e. Grania monochaeta (Michaelsen, 1888) and Grania lasserrei Rota & Erséus, 1997, share the presence of a midventral copulatory gland (in segment XIV) with G. brasiliensis sp. nov. A third species from the same island, Grania stephensoniana Rota & Erséus, 1997, also seems to have this gland, but it was not clearly seen because of the poor quality of the specimens available for the original description (see Rota & Erséus, 1997); G. stephensoniana is also larger than all the other species just mentioned. Grania monochaeta is similar to G. brasiliensis sp. nov. in the location of the spermathecal pores (at some distance from 4/5), but it has glands at its spermathecal pores and stylets in its penial bulbs; G. brasiliensis sp. nov. lacks these characters. Both G. lasserrei and G. stephensoniana possess a head organ (Rota & Erséus, 1996), a structure observed neither in G. brasiliensis sp. nov. nor in G. monochaeta.

The presence of a copulatory gland in segment XIV is also characteristic of the Tasmanian species Grania tasmaniae Rota & Erséus, 2000, but like G. lasserrei and G. stephensoniana, this species also has a head organ, and furthermore, an unusual type of coelomocytes; according to Rota & Erséus (2000), these cells resemble the spindle-shaped coelomocytes found in Cernosvitoviella and some species of Chamaedrilus (formerly Cognettia; see Martinsson, Rota & Erséus, 2014).

Despite sharing some characters with G. brasiliensis sp. nov., all of the species from South Africa described below (see their respective remarks), have sperm funnels that are short, not long as in the G. brasiliensis sp. nov., and a clitellar epidermis that seems to contain only granular cells (no rows of hyaline cells as in the Brazilian species).

The length of the sperm funnels and the absence of stylets also distinguish G. brasiliensis sp. nov. from the Caribbean Grania bermudensis Erséus & Lasserre, 1976, Grania laxartus Locke & Coates, 1999, and Grania hylae Locke & Coates, 1999. Moreover, these species differ from G. brasiliensis sp. nov. by their complex penial apparatus, and the presence of a head organ in both G. laxartus and G. hylae.

Among the Grania species with elongate sperm funnels, a pattern of clitellar cells similar to that in G. brasiliensis sp. nov., i.e. alternating rows of granular and hyaline cells, has also been described for the Western Australian Grania sperantia Rota, Wang & Erséus, 2007; however, this species lacks lateral chaetae and has an unsually long clitellum (extending over segments XI–XIII and sometimes over a part of segment XIV), with a thicker and more complex ‘multiband’ pattern, i.e. the hyaline cells are more numerous than the granular cells only at the two ends (‘borders of clitellum’; Rota et al., 2007).

The sperm funnels are very long (between nine and 18 times longer than wide), in G. brasiliensis sp. nov. and G. sperantia, as well as in the other Australian species Grania conjuncta Coates & Stacey, 1993, Grania vacivasa Coates & Stacey, 1993, Grania eurystila Coates & Stacey, 1997, and Grania integra Coates & Stacey, 1997; however, all these species are totally devoid of lateral chaetae, which is not the case in G. brasiliensis sp. nov.