Grania carolinensis, Prantoni & Wit & Erséus, 2016

Prantoni, Alessandro Lívio, Wit, Pierre De & Erséus, Christer, 2016, First reports of Grania (Clitellata: Enchytraeidae) from Africa and South America: molecular phylogeny and descriptions of nine new species, Zoological Journal of the Linnean Society 176 (3), pp. 485-510 : 501-502

GRANIA CAROLINENSIS SP. NOV.

FIGURE 10

Holotype

USNM 1283174 , CE11569, whole-mounted, sexually mature specimen, with some segments amputated, from off North Carolina, USA, 33°10′23″N, 76°45′23″W. Continental shelf slope, 492 m in depth, sand. Collected by C. Erséus, 20 May 2011. COI barcode sequence, GenBank acc. no. KT428112 ; for other sequences, see Table 1 .

Etymology

Named for North Carolina. Description

Body> 5.10 mm long,> 30 segments (posterior end used for DNA extractions), 0.08 mm wide at segment V, 0.09 mm wide at segment XII. Prostomium rounded, 51 μm long, 66 μm wide, epidermis 10 μm thick, reduced to 4 μm at front tip. Ventral chaetae from segment XIII, lateral chaetae absent. Chaetae ( Fig. 10A ) 42–50 μm long, shaft straight, 3.7 μm thick at midpoint, L-shaped, proximally bent into a foot with low instep and slight heel. Chaetal index ( Rota & Erséus, 2003) 3.60 ± 0.33 (n = 4). Epidermal gland cells inconspicuous. Clitellum not well developed. Spermathecal pores in lateral lines, immediately posterior to 4/5. Male pores ventrolateral in mid-segment XII. Female pores not observed.

Brain posteriorly indented. Head organ (sensu Rota & Erséus, 1996) absent. Pharyngeal glands in segments IV–VI, dorsal lobes in segment IV (one pair), in segment V (one pair), and in segment VI (one pair), ventral lobes present in segment IV (one pair), in segment V (two pairs), and in segment VI (two pairs); glands not connected dorsally. Nephridia not observed. Chloragogen cells not observed. Dorsal blood vessel commencing in segment XVII. Coelomocytes not observed. Sperm sac extending into half of segment XV, egg sac extending into segment XVII. Sperm funnels about six times longer than wide ( Fig. 10C ). Vasa deferentia observed in segments XII–XIII, internally ciliated, coiled, 7 μm wide. Penial apparatus type 1 (sensu Coates, 1984), small, glandular bulb, 40 μm long, 31 μm wide; stylet absent. Midventral copulatory gland (in segment XIV) not observed. Each spermatheca attached to oesophagus in posterior half of segment V. Ampulla large, oval, 100 μm long, 44 μm wide. Sperm rings maximally 11 μm wide, but few. Ectal duct slender, 53 μm long, 14 μm wide at midcourse, narrowing at distal end Figure 10B ). No gland at spermathecal pore.

Remarks

Grania carolinensis sp. nov. is similar to the northeast Atlantic, Grania postclitellochaeta ( Knöllner, 1935) , Grania ovitheca Erséus, 1977 , and the cryptic congener to G. ovitheca , Grania occulta De Wit & Erséus, 2010 , a species constellation also supported by the genetic data (see ‘Phylogenetic analyses’ below). All of these four species have the same distribution of ventral chaetae (beginning in segment XIII), and they lack lateral chaetae and the midventral copulatory gland in segment XIV. Grania carolinensis sp. nov., G. ovitheca , and G. occulta also share the shape of the spermatheca, which has a short and slender ectal duct and a large oval ampulla. In G. ovitheca and G. occulta , however, the sperm funnels are longer (between eight and 15 times longer than wide, as opposed to six times longer than wide in G. carolinensis sp. nov.) and they lack the ventral lobes of the pharyngeal glands in segment IV that are present in G. carolinensis sp. nov. and also in G. postclitellochaeta . Grania postclitellochaeta differs from G. carolinensis sp. nov. by possessing a racketshaped diverticulum in the spermathecal ampulla, which is absent in G. carolinensis sp. nov. In addition, G. carolinensis sp. nov. differs from all the species mentioned above by its penial apparatus, with a simple invagination surrounded by a small and glandular bulb. In G. postclitellochaeta the penial bulbs are covered by a large supplementary glandular body, whereas in G. ovitheca the bulbs instead have lateral aglandular sacs directed posteriorly ( Rota & Erséus, 2003). The aglandular sacs were not mentioned in the original description of G. occulta (see De Wit & Erséus, 2010), but the authors noted that the single available specimen possessed oval structures next to the epidermal invaginations. No accessory glands or sacs could be observed near the male pores of G. carolinensis sp. nov. The deep-sea Atlantic Grania atlantica Coates & Erséus, 1985 also resembles G. carolinensis sp. nov. by the proportions of the sperm funnel and the morphology of the penial apparatus, but the former differs from the latter by its spermathecal ampulla, which has a large sacciform diverticulum. Moreover, G. atlantica possesses lateral chaetae, a head organ, as well as a midventral copulatory gland in segment XIV, all of which are absent in the new species.

Figures

Figure 10. Grania carolinensis sp. nov. A, chaetae. B, spermatheca. C, penial bulb and sperm funnel. See text for abbreviations.