Crassolabium aenigmaticum, Vu & Ciobanu & Abolafia & Peña-Santiago, 2010
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publication ID |
https://doi.org/ 10.1080/00222933.2010.481055 |
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persistent identifier |
https://treatment.plazi.org/id/E759B624-FFC4-4B01-4EC1-E5677121FD5E |
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treatment provided by |
Felipe |
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scientific name |
Crassolabium aenigmaticum |
| status |
sp. nov. |
Crassolabium aenigmaticum sp. nov.
( Figures 1–3 View Figure 1 View Figure 2 View Figure 3 )
Material examined
Fourteen females, seven males and four juveniles in acceptable state of conservation.
Measurements
See Table 1.
Description
Adult. Moderately slender to slender medium-sized nematodes, 1.23–1.58 mm long. Body cylindrical, tapering towards the anterior end. Habitus more or less curved ventrad upon fixation, adopting an open C-shape in females, and most curved ventrad in posterior body region in males. Cuticle with very fine transverse striations, sometimes difficult to distinguish; it is 2.5–3.5 µm thick in anterior region, 3.0–4.0 µm at mid-body and 6.0–8.5 µm on tail. Lateral chord 5.0–8.0 µm wide at mid-body, occupying less than one-fifth (11–17%) of corresponding body diameter at midbody. Lip region rounded, continuous with adjacent body, 2.6–3.2 times as broad as high and about one-third (31–37%) of body diameter at neck base; lips almost completely amalgamated; labial and cephalic papillae very slightly protruding. Amphid fovea relatively small, goblet-like, its opening occupying 4.0 µm or less than one-third (30%) of lip region diameter. Odontostyle quite robust, wider than cuticle at its level, and 1.1–1.3 times the lip region diameter long, 4.1–5.3 times as
Notes: Scale bars, (A) 200 µm; (B–D, G, I–M) 10 µm; (E, F, H) 20 µm.
Notes: Scale bars, (A) 200 µm; (B–E, G–I) 10 µm; (F) 20 µm.
long as wide and 1.2–1.4% of body length; aperture occupying 43–47% of total length. Guiding ring thin, simple, plicate. Odontophore about twice the odontostyle, its inner lining distinctly irregular or wrinkled (?artefact, see remarks). Pharynx consisting of a slender, but muscular anterior portion enlarging gradually; basal expansion 5.6–8.8 times as long as broad, 3.2–4.6 times longer than body diameter at neck base, and occupying about half (48–51%) of total neck length; pharyngeal gland nuclei in general obscure in the specimens examined, but their outlets quite distinct and situated as follows: DO = 52–56, DN = 53–59, S 1 O 1 = 64–67, S 1 O 2 = 6 8–72, S 2 O = 80–84, being remarkable in the anterior position of DO and, in particular, S 2 O. Nerve ring located at 32–41% of total neck length. Cardia conoid, 9.0–20.0 × 8.0–15.0 µm long.
Female. Genital system didelphic–amphidelphic. Ovary reflexed, moderately developed, sometimes reaching and surpassing the sphincter level; the anterior ovary 56.0–121.0 µm, the posterior 77.0–187.0 µm long; oocytes arranged first in several rows and then in single row. Genital tract often convoluted and containing sperm and uterine eggs, so the morphometrics provided, especially those of uterus, might not be very precise. Oviduct joining ovary subterminally, 54.0–90.0 µm long or 1.2–2.0 body diameters, and consisting of a tubular part and a well-developed pars dilatata. A distinct sphincter separates the oviduct from uterus. Uterus long, tripartite, i.e. consisting of a wider proximal region with distinct lumen, a more slender intermediate with narrow lumen and a moderately developed, spherical, distal part; 86.0–160.0 µm long or 2.2–3.0 times as long as corresponding body diameter. Uterine eggs measuring 93.0–101.0 × 37.0–43.0 µm. Vagina extending inwards 46–62% of corresponding body diameter; pars proximalis shorter than wide, 7.0–12.5 ×15.0–17.0 µm, with sigmoid walls and surrounded by moderately developed musculature; pars refringens with (in lateral view) two distinct, triangular, separated pieces, measuring 5.5–9.5 ×4.5–6.0 µm, with a less refractive intermediate area, and with a combined width of 13.5–16.0 µm; pars distalis short, measuring 2.0–4.0 µm. Vulva a post-equatorial longitudinal slit appearing in lateral view like a short longitudinal depression. Ovoid spermatozoa, 4.5–5.0 µm long present in the genital tract of some females. Pre-rectum 1.1–2.2 anal body diameter long. Rectum 0.8–1.2 times anal body diameter. Tail short and rounded, almost hemispherical, slightly clavate in some specimens. A prominent terminal digitation was observed in only one female. Two pairs of caudal pores, one subdorsal, other lateral or subventral.
Male. Genital system diorchic, with opposite testes. In addition to ad-cloacal pair, there is a series of seven to eight widely separated (10.0–16.0 µm apart) ventromedian supplements, outside the range of spicules; hindermost ventromedian supplement located at 33.0–45.0 µm from ad-cloacal pair. Spicules quite robust, 1.3–1.5 anal body diameters long, 4.2–4.8 times as long as wide. Lateral guiding pieces cylindrical, 10.0–11.0 µm long, 3.1–4.4 times as long as wide. Pre-rectum 1.5–3.3, cloaca 1.0–1.4 times the anal body diameter long. Tail short and rounded, ventrally somewhat more straight. Two pairs of caudal pores, one subdorsal, other lateral.
Juvenile (J4). Similar in morphology to adult, but with tail consisting of two parts: anterior section convex conoid to rounded, almost as long as anal body diameter; and posterior section cylindrical, longer than anterior one and bent dorsad. Basic measurements: body length 1.02 mm, neck length 294.0 µm, functional odontostyle 16.5 µm, and substitution odontostyle 19.0 µm.
Diagnosis
This species is characterized by its body, 1.23–1.58 mm long, lip region continuous with adjacent body and 13.5–15.5 µm wide, odontostyle 17.0–19.0 µm long with aperture occupying 43–47% its length, odontophore irregular or wrinkled (see also remarks), neck 320.0–397.0 µm long, pharyngeal expansion 140.0–194.0 µm long or occupying 44–51% of total neck length, female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two triangular pieces separated by an intermediate sclerotized area, V =54–59, vulva longitudinal, tail short and rounded (16.0–20.0 µm, c =70–84, c’ = 0.5–0.7 in females, but see footnote in Table 1), spicules 43–48 µm long, and seven to eight spaced ventromedian supplements.
Relationships
This species shows a peculiar combination of characters that make its identification an intriguing matter. Particularly interesting is the existence of juveniles with elongate tails while adults are short-tailed.
In having guiding ring simple, female genital system amphidelphic, short rounded tail and well spaced ventromedian supplements, this species comes close to members of Crassolabium Yeates, 1967 , especially C. garhwaliense (Ahmad, Nath and Haider, 1985) , C. goaense (Ahmad, 1993) , C. lautum (Andrássy, 1959) and C. rhopalocercum (de Man, 1876) . It differs from C. garhwaliense in its larger general size (vs. body 1.07–1.13 mm long), lip region continuous (vs. offset by a marked depression), longer odontostyle (vs. 15.0–16.0 µm), pars refringens vaginae with two separate (vs. close together) pieces, longer spicules (vs. 37.0–38.0 µm), and fewer ventromedian supplements (vs. 10); from C. goaense , a similar species, in its larger size (vs. body 0.78–1.00 mm), narrower lip region (vs. 11.0–12.0 µm), tripartite uterus (vs. apparently a simple tube), more anterior vulva (vs. V =58–64), and presence (vs. absence) of males; from C. lautum , only known from males, by having shorter odontostyle (vs. 21.0 µm), more rounded and shorter tail (vs. conoid, 26.0 µm long), and fewer (vs. 13) of spaced (vs. almost contiguous) ventromedian supplements; and from C. rhopalocercum by its pars refringens vaginae consisting of two well-developed pieces, separated by a sclerotized intermediate area (vs. two small, close together pieces), vulva longitudinal (vs. transverse) and more posterior (vs. V = 44–49), and males present (vs. absent).
On the other hand, the new species is rather similar to the only species of the genus Skibbenema Van Reenen and Heyns, 1986 , namely S. constrictum , also with comparable elongate-tailed juveniles, but this genus is characterized by having a distinct constriction between both pharyngeal regions, as well as a bipartite pharyngeal expansion, two very atypical features within qudsianematid taxa; moreover, S 2 O is significantly more anterior (vs. S 2 O = 95–98). It is also reminiscent of some Labronema species , for instance L. ferox Thorne, 1939 and L. thornei Ferris, 1968 , having elongated-tailed juveniles too ( Ferris 1968), but the new species does not fit the general Labronema pattern: lip region offset by constriction, guiding ring double and male ventromedian supplements contiguous, among other features.
It also resembles the qudsianematid genus Sphaeroamphis Ahmad and Sturhan, 2000 in having continuous lip region, amphidial fovea with comparatively small aperture, odontostyle rather robust, and rounded, slightly clavate female tail. However, it can be distinguished from this taxon by its well-developed pars refringens vaginae (vs. lacking), more anterior location of S 2 O, and ventromedian supplements out the range of spicules (vs. no hiatus, with ventromedian supplements within spicules range).
Finally, by its general aspect, continuous lip region and, very especially, the anterior location of S 2 O, the new species resembles the members of Willinema Baqri and Jairajpuri, 1967 ( Thornenematidae , Willinematinae ; see revision by Carbonell and Coomans [1984]), but it differs from these in having larger size (vs. body length up to 1.2 mm), female genital system amphidelphic (vs. mono- or pseudomono-opisthodelphic) and longitudinal vulva (vs. transverse).
Type habitat and locality
Tropical evergreen forest soil with tree vegetation consisting of Hopea sp. , Dipterocarpus sp. , Quercus sp. , Lithocarpus sp. , Castanopsis sp. , Cinnamomum sp. , Litsea sp. within the Pu Mat National Park (geographical coordinates: 18º 46′ N to 19º 12′ N and 104º 24′ E to 104º 56′ E), Nghe An province, Vietnam.
Type material
Female holotype and two female paratypes on slide 0502, three female and three male paratypes on slides 0503–0506 deposited in the nematode collection of Departamento de Biología Animal , Biología Vegetal y Ecología, University of Jaén, Spain ; six female paratypes and one male paratype deposited on slides [DQ-01] and [DQ-02] in Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam .
Etymology
The specific epithet refers to the intriguing filiation of the new species. Remarks
For practical reasons, this species is classified under the genus Crassolabium , since it fits better the morphological pattern of this taxon. However, the anterior location of S 2 O, and, in particular, the existence of elongate-tailed juveniles are remarkable features and raise some doubts about its true identity. Unfortunately, there is no relevant information concerning tail morphology in juveniles of other Crassolabium species , so a further analysis of this matter is not possible at this moment. A comparison of the new species with C. goaense , a close Asian species with S 2 O also located very anteriorly, would be interesting and useful.
The nature of the odontophore deserves a special comment. In every specimen it appears with an irregular or wrinkled outline, and the first impression is that this feature might be an artefact owing to bad fixation. Nevertheless, (1) it occurs in specimens of different soil samples; (2) the specimens are in general in acceptable state of conservation, suggesting that fixation was properly carried out; and (3) other dorylaimid species found in the same soil samples do not have a comparable or similar aspect in their odontophore. Although it should be considered with due caution, odontophore morphology might be another relevant diagnostic feature of this species.
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