Aporcelaimellus deserticola, Álvarez-Ortega, Sergio, Abolafia, Joaquín & Peña-Santiago, Reyes, 2013

Álvarez-Ortega, Sergio, Abolafia, Joaquín & Peña-Santiago, Reyes, 2013, Studies on the genus Aporcelaimellus Heyns, 1965 (Nematoda, Dorylaimida, Aporcelaimidae). Four atypical species with simple uterus from Southern Iberian Peninsula, Zootaxa 3630 (3), pp. 401-423 : 402-406

Aporcelaimellus deserticola sp. n.

( Figs 1 & 2 )

Material examined. Fourteen females from two populations, in good state of preservation. Measurements. See Table 1 .

Population Tabernas Desert

Gergal old road Minihollywood Holotype Paratypes

Description. Female: Slender nematodes of medium size, 1.79–2.43 mm long. Body cylindrical, tapering towards both extremities, but more so towards the posterior end because the tail is conical. Habitus curved ventrad after fixation, especially in posterior body region, C-shaped. Cuticle three-layered, 1.0–1.5 μm thick at anterior region, 2–3 μm in mid-body and 3.0–4.5 μm on tail; outer layer thin and bearing fine but distinct transverse striation throughout the entire body, intermediate layer also thin, and inner layer thicker than the others. Cervical lacunae absent. Lateral chord 9–15 μm wide or 16–24% of mid-body diameter. Lip region offset by expansion rather than by constriction, 2.7–2.9 times as wide as high and one-fourth to one-third (24–33%) of body diameter at neck base; lips somewhat angular and separated, with moderately protruding papillae. Amphid fovea funnelshaped, aperture 7–9 μm or four-ninths to four-sevenths (44–58%) of lip region diameter. Cheilostom nearly cylindrical, lacking any differentiation. Odontostyle 5.0–5.8 times as long as wide, 1.1–1.3 times as long as lip region diameter, and 0.93–0.98% of body length; aperture 10–12 μm long or occupying five-ninths to three-fifths (55–61%) its length. Guiding ring plicate. Odontophore linear, rod-like, 1.4–1.6 times the odontostyle. Anterior region of pharynx enlarging very gradually; basal expansion 6.7–9.8 times as long as wide, 4.0–5.2 times as long as body diameter, and occupying 49–52% of total neck length; pharyngeal gland nuclei located as follows: DN = 60–63; S1N1 = 73–76; S1N2 = 79–82; S2N = 90–92. Nerve ring located at 148–192 μm from anterior end or 30–33% of total neck length. Cardia conical, 11– 22 x 9–16 μm; its junction to pharyngeal base surrounded by a weak ringlike structure. A dorsal cell mass is present at level of the anterior end of intestine. Genital system didelphicamphidelphic, both branches relatively small, the anterior 119–175 μm or 6–8% of body length, and the posterior 115–165 μm or 6–7% of body length; ovaries varying in size, the anterior 58–137 μm and the posterior 64–153 μm long, with oocytes arranged first in two or more rows, then in a single row; oviduct 53–74 μm long or 0.8–1.3 times the corresponding body diameter, consisting of a slender part with prismatic cells and a moderately developed pars dilatata with visible lumen; oviduct-uterus junction marked by a narrowing and a weak sphincter; uterus a simple tube 34–67 μm long or 0.6–1.1 times the corresponding body diameter; vagina extending inwards 21–27 μm or one-third to four-ninths (33–47%) of body diameter, consisting of pars proximalis 15– 20 x 18–22 μm and with somewhat sigmoid walls surrounded by weak musculature, pars refringens with two triangular to rounded pieces measuring 4– 7 x 2.5–5.0 μm and with a combined width of 10–13 µm, and pars distalis short, 1.5–3.0 μm; vulva a nearly equatorial, transverse slit. Prerectum 1.3–3.3, rectum 1.3–1.8 times the anal body diameter. Tail conical with broadly rounded terminus, ventrally straighter; a short but perceptible, terminal hyaline portion is always present between the cuticle layers; caudal pores two pairs, one lateral and another subdorsal.

Male: Not found.

Diagnosis. This species is characterized by a body length of 1.79–2.43 mm, lip region offset by expansion rather than by constriction and 14–16 μm broad, odontostyle 18–21 μm long with aperture occupying 55–61% of its length, neck 464–555 μm long, pharyngeal expansion 234–283 μm long or 49–52% of total neck length, a dorsal cell mass present at level of anterior end of intestine, uterus simple and 34–67 μm long or 0.6–1.1 times the corresponding body diameter, V = 49–55, tail conical with rounded terminus (29–43 μm, c = 47–66, c’ = 0.9–1.4) and bearing a short but perceptible hyaline portion, and male unknown.

Relationships. In having medium size, comparatively narrow lip region, relatively short odontostyle and simple uterus A. deserticola sp. n. is morphologically close to several other Aporcelaimellus species, namely A. amylovorus (Thorne & Swanger, 1936) Heyns, 1965 , A. brevicaudatus Álvarez-Ortega, Abolafia & Peña-Santiago, 2013 , A. clamus Thorne, 1974 , A. rotundus Álvarez-Ortega, Abolafia & Peña-Santiago, 2013 , A. salicinus Álvarez- Ortega, Subbotin & Peña-Santiago, 2013, A. samarcandicus (Tulaganov, 1949) Baqri & Khera, 1975 , and A. waenga (Yeates, 1967) Peña-Santiago & Ciobanu, 2008 (= A. laevis Tjepkema, Ferris & Ferris, 1971 ), but it can be separated from these in the morphology of lip region (angular and offset by expansion rather than by constriction vs more rounded and offset by deep constriction, not expanded-like). In addition, it differs from A. amylovorus (see re-description by De Ley et al., 1993) in its longer general size (vs body 1.63–1.79 mm long; neck 382–406 µm long), comparatively shorter odontophore (1.4–1.6 vs 1.7–2.3 times the odontostyle length), more anterior location of DN and more posterior location of S2N (DN = 60–63 vs 64–65; S2N = 90–92 vs 88–89), and conical tail (vs bluntly convex-conoid) bearing perceptible (vs lacking) hyaline portion. From A. brevicaudatus in its longer odontostyle (vs 13–15 µm; 1.1–1.3 vs 0.9 times as long as lip region diameter) with shorter aperture (vs 70–75% its length), shorter neck (b = 3.8–4.5 vs b = 3.6), and conical (vs rounded to hemispheroid) and longer (vs 24–27 µm long, c’ = 0.6–0.7) tail. From A. clamus (see recent description by Álvarez-Ortega and Peña-Santiago, 2010) in its narrower lip region (vs 17.0–17.5 µm broad), comparatively longer (1.1–1.3 vs as long as lip region diameter; 0.93–0.98% vs 0.78–0.82% of body length) and more slender odontostyle (5.0–5.8 vs 4.5–4.6 times as long as wide) with smaller aperture (vs 70–73% of total length), arrangement of pharyngeal gland nuclei (DN = 60–63 vs 58–59; S1N2 = 79–82 vs 85–86; S2N = 90–92 vs 93–94), female tail conical (vs convex-conoid), and male absent (vs present). From A. rotundus in its lip region angular (vs more rounded) and narrower (vs 19–20 μm broad), shorter odontostyle (vs 22–23 μm long), and comparatively longer tail (vs c’ = 0.7–0.9) bearing a short hyaline portion (vs lacking any hyaline terminal portion). From A. salicinus , a very similar species, in its comparatively shorter (0.93–0.98%, n=14 vs 1.01–1.28% of body length, n=15) and more robust odontostyle (5.0–5.8 vs 5.8–6.3 times as long as wide) with larger aperture (vs 50–53% of total length), more anterior location of DN (60–63 vs 63–68), and caudal region with different morphology (inner core occupying more vs less than four-fifths of total length, and lacking vs usually bearing distinct refringent bands). From A. samarcandicus (mainly based on data provided by Andrássy, 2002) in its longer (vs 1.47–1.70 mm) and more slender (a = 29–37 vs a = 25–29) body, narrower lip region (vs 17–19 µm broad), cervical lacunae absent (vs present, according to Fig.14A in Andrássy, 2002), and longer (vs 20–26 µm, c’ = 0.6–0.7) and conical (vs convex-conoid) tail. And from A. waenga (see recent description by Álvarez-Ortega et al., 2013a) in its comparatively longer (1.1–1.3 vs 0.8–1.0 times as long as lip region diameter) and more slender odontostyle (5.0–5.8 vs 4.1–4.9 times as long as wide), comparatively shorter odontophore (1.4–1.6 vs 1.7–2.0 times the odontostyle length), more posterior location of pharyngeal gland nuclei (DN = 60–63 vs DN = 54–59; S1N1 = 73–76 vs 65–70; S1N2 = 79–82 vs 71–77; S2N = 90–92 vs 80–86), and conical tail (vs convex-conoid).

The new species also resembles A. alius Andrássy, 2002 , A. medius Andrássy, 2002 and A. obtusicaudatus (Bastian, 1865) Altherr, 1968 (see recent concept of this species by Álvarez-Ortega & Peña-Santiago, 2012). It can be distinguished from A. alius in its more slender body (a = 29–37 vs a = 20–24), narrower lip region (vs 18–19 µm broad), cervical lacunae absent (vs present, according with the original Fig.17A in Andrássy, 2002), shorter odontostyle (vs 21–23 µm long), vulva more posterior (vs V = 46–49) and tail conical (vs convex-conoid) lacking (vs bearing) any dorsal concavity. From A. medius in its more slender body (a = 29–37 vs a = 20–26), narrower lip region (vs 17–18 µm), cervical lacunae absent (vs present, according to the original Fig.15A in Andrássy, 2002), shorter odontostyle (vs 22–23 µm long), female tail conical (vs convex-conoid to hemispheroid) and longer (vs 15–23 µm, c = 90–140, c’ = 0.4–0.5), and absence of males (vs present). And from A. obtusicaudatus in its narrower lip region (vs 16–23 µm broad), cervical lacunae absent (vs usually present), comparatively longer odontostyle (1.1–1.3 vs 0.9–1.1 times as long as lip region diameter), posterior location of the two pairs of pharyngeal gland nuclei (S1N1 = 73–76, S1N2 = 79–82, S2N = 90–92 vs S1N1 = 64–74, S1N2 = 72–80, S2N = 81–90), and male absent (vs present).

Type locality and habitat. Spain, eastern Andalucía, Almería province, “Tabernas Desert”, old road to Gergal, associated with Retama sphaerocarpa and esparto (needle grass: Macrochloa tenacissima ) field.

Other locality and habitat. The new species also was collected from Spain, eastern Andalucía, Almería province, “Tabernas Desert”, Miniholliwood, associated with thyme ( Thymus sp.), Cistus sp. and Retama sphaerocarpa .

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

Etymology. The specific epithet refers to the habitat in which the species was collected.

Figures

FIGURE 1. Aporcelaimellus deserticola sp. n. (female). A: Anterior region in median view. B: Same in lateral, surface view. C: Pharyngeal expansion. D: Anterior genital branch. E: Entire body. F: Posterior body region. G, H: Vagina.

FIGURE 2. Aporcelaimellus deserticola sp. n. (LM, female). A: Entire. B, C: Anterior region in median, lateral view. D: Vagina and uterus. E: Pharyngeal expansion. F: Posterior body region. G: Lip region in lateral, surface view. H: Anterior genital branch. I: Pharyngo-intestinal junction. J, K: Caudal region. (Scale bars: A = 500 µm; B, I = 20 µm; C, D, J, K = 10 µm; E = 100 µm; F, H = 50 µm; G = 5 µm).

Tables

TABLE 1. Morphometric data of Aporcelaimellus deserticola sp. n. Measurements in μm (except L, in mm), and in the form: mean ± standard deviation (range).

Character	n Ƥ	9ƤƤ	4ƤƤ
L	2.31	2.09 ± 0.20 (1.79–2.43)	2.17 ± 0.14 (2.01–2.33)
a	37	32.7 ± 2.3 (29–37)	33.4 ± 1.4 (32–34)
b	4.3	4.2 ± 0.2 (3.8–4.5)	4.0 ± 0.2 (3.8–4.2)
c	59	59 ± 6 (49–66)	54 ± 5 (47–58)
c'	1.3	1.2 ± 0.2 (0.9–1.4)	1.2 ± 0.1 (1.1–1.3)
V	53	51.5 ± 1.6 (50–55)	51.1 ± 1.4 (49–53)
Lip region diam.	15	15.0 ± 0.4 (14–16)	15.6 ± 0.5 (15–16)
Odontostyle length	19	18.6 ± 0.9 (18–20)	20.2 ± 0.6 (19–21)
Odontophore length	28	27.9 ± 1.1 (26–29)	29.3 ± 1.0 (28–30)
Guiding ring from ant. end	8	8.8 ± 0.5 (8–10)	8.7 ± 0.7 (8–10)
Neck length	537	502 ± 28 (464–541)	543 ± 17 (524–555)
Pharyngeal expansion length	273	256 ± 16 (234–283)	274 ± 4 (272–278)
Diam. at neck base	54	56.7 ± 6.9 (45–68)	64.0 ± 1.6 (62–66)
at mid-body	63	63.9 ± 6.5 (55–77)	65.6 ± 2.8 (63–69)
at anus	29	31.3 ± 3.1 (28–38)	33.7 ± 0.9 (33–35)
Prerectum length	81	67.8 ± 14.6 (45–86)	96.6 ± 14.2 (79–110)
Rectum length	51	48.4 ± 2.1 (46–52)	46.7 ± 2.6 (45–51)
Tail length	39	35.8 ± 3.6 (29–43)	40.5 ± 2.3 (38–43)