Tubificoides charlotteae Kvist & Erséus 2018, n. sp.
Creators: name: Kvist, Sebastian
name: Erséus, Christer
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Clitellata
Haplotaxida
Tubificidae
Tubificoides
Tubificoides charlotteae

description: Tubificoides charlotteae n. sp.
Figures 1, 2
Tubificoides " amplivasatus II"; Kvist et al. 2010
Diagnosis. This species can be distinguished from congeners on the basis of its possession of hair chaetae, its lack of cuticular papillation, its relatively small body size, and in the details of its male genital ducts. In comparison with its closest relative, T. amplivasatus, its body is smaller and its vas deferens narrower. In addition, whereas the ejaculatory duct is long and not incorporated in the penial sac in T. amplivasatus, the same structure is short and enclosed by the musculature of the penial sac in T. charlotteae. The average COI distance between T. charlotteae n. sp. and T. amplivasatus is 12.74% (see Kvist et al. 2010) and a total of 78 characteristic attributes (i.e., molecular synapomorphies; see Sarkar et al. 2002) separate the COI sequences of these species (Kvist et al. 2010).
Holotype. SMNH Type coll. 8952 (formerly SMNH 108958; specimen ID CE 1247 in Kvist et al. 2010), stained, whole-mount on microscope slide with coverslip, sexually mature specimen, collected by C. Erséus, Nov. 21 2005; holotype COI sequence GenBank accession number HM460169; for other genetic information, see details in Kvist et al. (2010).
Type locality. San Pedro River, Puerto Real, Cadiz, Andalucía, Spain, intertidal (36°33'24"N, 06°12'23"W).
Paratypes. SMNH Type Coll. 8953 (formerly SMNH 108959; specimen ID CE 1248 in Kvist et al. 2010) and 8954 (formerly SMNH 108960; specimen ID CE 1249 in Kvist et al. 2010), stained, whole-mounts on microscope slide with coverslip, both specimens mature, collected at type locality by C. Erséus, Nov. 21 2005; for genetic information, see Kvist et al. (2010). Paratypes COI sequence GenBank accession numbers HM460170 and HM460171.
Etymology. Named in honor of Charlotte Calmerfalk Kvist - the first author is eternally grateful for her tireless support, patience and love during years of focus on clitellate research.
Description. All types incomplete, posterior ends used for DNA extraction. Holotype 1.58 mm long with anterior 13 segments (Fig. 1A), paratypes 1.5–2.4 mm long with anterior 12–22 segments. Width at XI 0.28 mm in holotype, 0.15–0.30 mm in remaining specimens; all specimens mounted and compressed. Prostomium bluntly conical in most specimens (Fig. 1A), more pointed in one paratype, slightly shorter than basally wide. Cuticle smooth in anterior portion, densely and finely granulate in posterior part, aspect somewhat "dusty" (Fig. 1A), but proper cuticular papillae nowhere developed. Clitellum poorly developed in segments X–XI of all type specimens.
In preclitellar segments, dorsal chaetal bundles with (1)2–3 needle-like hair chaetae (up to 100 µm long) and 1–3 bifid crotchets, 25–35 µm long (Fig. 2A). Bifids with straight teeth of equal length and approximately same width. Postclitellar dorsal bundles with 1–3 hair chaetae (about 50 µm long) and 1(2) bifid crotchets, 25–30 µm long (Fig. 2B); bifids straight, with teeth of equal length and approximately same width. Some bundles without bifids (tips broken off?). Preclitellar ventral bundles (Fig. 2C) with 2–3 bifid crotchets (25–50 µm long), sometimes transitioning into a single bifid in "bundles" closer to genital region; teeth of equal length, upper tooth thinner than lower and teeth rather diverging. No ventral chaetae in segment XI of mature worms. Postclitellar ventral "bundles" (Fig. 2D) each represented by a single bifid crotchet (at least 20–25 µm long), both teeth becoming increasingly thinner posteriorly, with approximately same width; chaetae are in an oblique position. Nodulus inconspicuous in all bifid crotchets. Spermathecal pores paired, located slightly above ventral chateae in X. Male pores paired, in line with or slightly above assumed ventral chaetal line in mid XI.
Pharyngeal glands present in IV–V, undetectable in one specimen. Esophagus possibly modified in IX but difficult to discern (see below, in the Remarks section for Tubificoides mackiei n. sp.). Vas deferens (Figs. 1D, 2E; vd) 25 µm wide in holotype, about 320 µm long (only measurable in one paratype). Vas rather thin-walled and densely ciliated; entering atrium (Figs. 1B, 2E; at) subapically and opposite to entrance of rather small prostate gland (Figs. 1B, 2E; pr). Atrium about 265 µm long in holotype, 45–60 µm wide; bipartite with dense and finely granulated cellular matrix in mid and ectal (closest to the external pore) portions, and coarser glandular epithelium in ental cap portion (inner portion, furthest away from external pore). Ectalmost end of atrium with short ejaculatory duct, leading into a muscular, egg-shaped penial sac, the latter about 50 µm long, 35 um wide (Figs. 1C, 2E). Cuticular penis sheath cone-shaped with terminal opening (Figs. 2E, 2F; cu); about 20 µm long, 25 µm wide. Poorly developed spermathecae visible in holotype and one paratype; spermatheca lightly pear-shaped with narrow duct (18 µm wide at narrowest point) leading to wider ental ampulla [about 170 µm long, 45 µm wide at widest part (Figs. 1E, 2G)]. All specimens pre-copulatory; spermatozeugmata not observed.
Distribution and habitat. Known only from type locality in southern Spain.
Remarks. Tubificoides charlotteae shares several features with, and seems closely related to, the north European species T. amplivasatus (see Kvist et al. 2010). First, the chaetal arrangement of T. charlotteae resembles that of T. amplivasatus inasmuch as both species possess dorsal hair chaetae and 1–3 bifid crotchets in anterior bundles. Second, the lack of cuticular papillation, but dense and fine granulation of the body wall, in the postclitellar region is reported for both species (Erséus 1975). Third, both species have unusually thin-walled vasa deferentia (Fig. 2E; Erséus 1975, Fig. 1 and Erséus 1976, Fig. 2), as well as cone-shaped penis sheaths. However, the new species differs from T. amplivasatus in its shorter body length (average of 0.2 mm per segment in T. amplivasatus versus 0.12 mm in T. charlotteae), lower number of dorsal hair chaetae (as many as four hair chaetae, reported in some bundles of T. amplivasatus, are nowhere found in T. charlotteae), in the width of the vas deferens (about 50 µm in T. amplivasatus, 25 µm in T. charlotteae), and in the shape and size of both the ejaculatory duct and penial sac. In T. amplivasatus, the ectal part of the male duct is a distinct ejaculatory duct (with a thin outer layer of circular musculature), and it is separated from the atrium proper by a constriction (Erséus 1976). This duct leads into the penis, which is located in a poorly developed penial sac (Erséus 1976, Fig. 2), and the latter does not enclose the ejaculatory duct. In T. charlotteae, however, the ejaculatory duct is short, its outer lining of muscles seen as a ring in Fig. 1C, and, here, the duct is enclosed by the strong musculature of the penial sac (Figs. 1C, 2E: psm).
description: Published as part of Kvist, Sebastian & Erséus, Christer, 2018, Two new European species of the marine genus Tubificoides (Annelida: Clitellata: Naididae) with notes on the morphology of T. pseudogaster (Dahl, 1960), pp. 561-573 in Zootaxa 4433 (3) on pages 563-564, DOI: 10.11646/zootaxa.4433.3.10, http://zenodo.org/record/1290333