Aporcelaimellus alpujarrensis, Álvarez-Ortega, Sergio, Abolafia, Joaquín, Liébanas, Gracia & Peña-Santiago, Reyes, 2012

Álvarez-Ortega, Sergio, Abolafia, Joaquín, Liébanas, Gracia & Peña-Santiago, Reyes, 2012, Studies on the genus Aporcelaimellus Heyns, 1965 (Nematoda, Dorylaimida, Aporcelaimidae). Four new species with complex uterus from Southeastern Iberian Peninsula, Zootaxa 3551, pp. 1-24 : 2-7

Aporcelaimellus alpujarrensis sp. n.

( Figs 1 & 2 )

Material examined. Five females and four males, in good state of preservation, except for pharynx and female genital system, often visibly convoluted.

Measurements. See Table 1.

Description. Adult: Moderately slender to slender nematodes of medium size, 1.72–1.91 mm long. Body cylindrical, tapering towards both extremities, but more so towards the posterior end. Habitus curved ventrad after fixation, C-shaped. Cuticle three-layered, 1.5–2.0 μm thick at anterior region, 3.0–4.5 μm in mid-body and 4.0–6.5 μm on tail; outer layer thin and bearing distinct transverse striation throughout the body, intermediate layer thin as well, and inner layer thicker than the others, especially visible at caudal region. Cervical lacunae well developed, always extending beyond the odontophore base. Lateral chord 6.5–10.5 μm wide or 11–18% of mid-body diameter; glandular bodies are readily perceptible in some specimens. Two ventral and two dorsal body pores are usually present at level of odontophore. Lip region offset by deep constriction, 2.9–3.1 times as wide as high and 23–29% (two-ninths to two-sevenths) of body diameter at neck base. Amphid fovea funnel-shaped, its aperture 8.5–9.0 μm or 58–64% (four-sevenths to two-thirds) of lip region diameter. Cheilostom nearly cylindrical, lacking any differentiation. Odontostyle typical of the genus, 4.4–5.1 times as long as wide, 1.0–1.1 times as long as lip region diameter, and 0.75–0.87% of body length; aperture 9.5–10.5 μm long or occupying about two-thirds (67–70%) its length. Guiding ring plicate. Odontophore linear, rod-like, 1.8–2.1 times the odontostyle length. Anterior region of pharynx enlarging very gradually; basal expansion 8.0 (n=1) times as long as wide, 3.7 (n=1) times as long as body diameter, and occupying 49% (n=1) of total neck length; pharyngeal gland nuclei obscure since the pharynx is convoluted in most specimens. Nerve ring located at 134–144 μm from anterior end or 31% (n=1) of total neck length. Cardia conical to rounded, 10– 16 x 12–13 μm; its junction with pharyngeal base surrounded by a weak ring-like structure, which appears more developed on its dorsal side, forming a small lobe. Tail convex-conoid, often slightly straighter on ventral side; intermediate cuticle layer thickened at tail terminus, forming a short but always distinct hyaline portion. Caudal pores in two pairs, one dorsal and other subdorsal.

Female: Genital system didelphic-amphidelphic, with both branches equally well developed, the anterior 272 μm (n=1) or 15% (n=1) of body length, and the posterior 264 μm (n=1) or 14% (n=1) of body length. Ovaries medium-sized, often not reaching the oviduct-uterus junction, the anterior 85–111 μm and the posterior 88–123 μm long; oocytes distally arranged in two or more rows, proximally in a single row. Oviduct 82–129 μm long or 1.2–1.9 times the corresponding body diameter, consisting of slender part with prismatic cells and a moderately developed pars dilatata. Oviduct and uterus are separated by a marked sphincter. Uterus 145–206 μm long or 2.2–3.1 times the corresponding body diameter, and tripartite, consisting of a spheroid distal portion close the sphincter, a slender and short intermediate section with very narrow lumen, and a larger, dilated proximal portion with wide lumen; sperm cells abundant inside distal and proximal uterine sections. Vagina extending inwards 24–29 μm or two-fifths to four-ninths (39–46%) of body diameter; pars proximalis 17– 23 x 16–19 μm, with somewhat sigmoid walls and surrounded by weak musculature; pars refringens with two triangular to rounded, small pieces measuring 5 x 3 μm and with a combined width of 8–11 µm; pars distalis short, 2–3 μm. Vulva a slightly post-equatorial, oval, transverse slit. Prerectum 2.1–3.8, rectum 1.1–1.7 times the anal body diameter.

Male: Genital system diorchic, with opposite testes. In addition to the ad-cloacal pair, situated at 13–14 μm from cloacal aperture, there is a series of 7–9 irregularly spaced (8–21 µm apart) ventromedian supplements, the posteriormost of which lies out the range of spicules at 58–70 μm from ad-cloacal pair. Spicules curved ventrad and slender, 6.4–6.6 times as long as wide, and 1.9–2.0 times as long as anal body diameter. Lateral guiding pieces 15–16 μm long, 6.5–8.0 times as long as wide. Prerectum 3.2–3.7, cloaca 1.5–1.7 times the anal body diameter.

Diagnosis. The new species is distinguishable by its body 1.72–1.91 mm long, lip region offset by constriction and 14–15 μm broad, odontostyle 14–16 μm long with aperture occupying 67–70% its length, neck 455 μm (n=1) long, pharyngeal expansion 224 μm (n=1) long or 49% of total neck length, uterus tripartite and 145–206 μm long or 2.2–3.1 times the corresponding body diameter, pars refringens vaginae present, V = 53–55, tail convex conoid (27–34 μm, c = 55–71, c’ = 0.9–1.1) with a short terminal hyaline portion, spicules 56–60 μm long, and 7–9 irregularly spaced ventromedian supplements bearing hiatus.

Relationships. The combination of three morphological features (comparatively narrow lip region, short odontostyle and, the most importantly, tripartite uterus) separates A. alpujarrensis sp. n. from its congeners.

In having medium body size (L = 1.72–1.91 mm), relatively narrow lip region (14–15 μm wide) and short odontostyle (14–16 µm long), the new species is morphologically close to a few species, namely A. amylovorus ( Thorne & Swanger, 1936) Heyns, 1965 , A. punctatus Altherr in Altherr & Delamare-Deboutteville, 1972, A. samarcandicus ( Tulaganov, 1949) Baqri & Khera, 1975 , and A. vanderlaani ( Meyl, 1957) Heyns, 1965 , from which it differs by its narrower lip region width (vs 15–21 μm wide) and shorter odontostyle (vs 17–19 μm). Moreover, it can be distinguished from A. amylovorus (mainly based on data provided by De Ley et al., 1993) by its larger odontostyle aperture (vs occupying 58–63% of total length), more complex and longer uterus (vs simple and 45 µm long), more posterior vulva (vs V = 50–53), comparatively shorter tail (vs c’ = 1.1–1.3), and presence of males (vs absent); from A. punctatus by its shorter body (vs L = 2.10 mm), shorter female genital branch (vs occupying 24–26% of body length), and presence of males (vs absent); from A. samarcandicus (mainly based on data provided by Andrássy, 2002a) by its larger general size (vs L = 1.47–1.70 mm), larger odontostyle aperture (vs occupying about one-half of total length or a little more), longer, tripartite uterus (vs shorter, less than two times the corresponding body diameter, and a simple tube in Andrássy’s Fig. 14C), and presence of males (vs absent); and from A. vanderlaani by its more posterior vulva (vs V = 50–51), comparatively longer tail (vs c’ = 0.7 in female and c’ = 0.6 in male), and lower number of ventromedian supplements (vs 10–11).

Finally, in having a tripartite uterus, A. alpujarrensis sp. n. is close to A. kikereensis Baqri & Coomans, 1973 , A. porosus Álvarez-Ortega, Ahmad & Peña-Santiago, 2011 , and A. propinquus ( Thorne & Swanger, 1936) Tjepkema, Ferris & Ferris, 1971 . It differs from A. kikereensis by its larger general size (vs L = 1.10–1.45), more slender body (vs a = 18–21), shorter odontostyle (vs 26–28 µm or 1.3–1.4 lip region widths long), more anterior vulva (vs V = 60–61), convex conoid female tail (vs conical digitate and dorsally bent), and presence of males (vs absent): from A. porosus by its smaller general size (vs L = 2.51–2.81 mm), narrower lip region (vs 19.5–21.5 µm), shorter odontostyle (vs 26–30 µm long), tail convex conoid and longer (vs more rounded and c’ = 0.5–0.7), shorter spicules (vs 81–87 µm), and ventromedian supplements bearing hiatus (vs lacking hiatus); and from A. propinquus by its larger general size (vs L = 1.06–1.18 mm, neck 286–329 µm long), larger odontostyle aperture (vs 42–47% of total length), longer spicules (vs 32–38 µm long) and lower number (vs 31–34) and irregularly spaced (vs almost continuous) of ventromedian supplements with hiatus (vs without hiatus).

Type locality and habitat. Southeastern Iberian Peninsula, province of Granada, Sierra Nevada Natural Park, Alpujarras Shire, where it was collected from soil in a pine forest.

Type material. Female holotype and three female and three male paratypes, deposited in the nematode collection of the University of Jaén, Spain. One female and one male paratypes deposited with USDA Nematode Collection, Beltsville, Maryland, USA.

Etymology. The specific epithet refers to the geographical origin of the species.

Figures

FIGURE 1. Aporcelaimellus alpujarrensis sp. n. A: Anterior region in median view. B: Same in lateral, surface view. C: Pharyngeal expansion. D: Anterior genital branch. E: Female, posterior body region. F: Male, posterior body region. G: Female, entire body. H: Male, entire body. I: Spicule and lateral guiding piece. J: Vagina.

FIGURE 2. Aporcelaimellus alpujarrensis sp. n. (LM). A: Female, entire. B: Male, entire. C, D: Anterior region in median, lateral view. E: Female, posterior genital branch. F: Vagina. G: Female, posterior body region. H: Male, posterior body region. I: Spicules. J: Lateral chord. K, L: Female, caudal region. M: Male, caudal region. (Scale bars: A, B = 500 µm; C, G, I, J = 20 µm; D, F, K-M = 10 µm; E = 100 µm; H = 50 µm).