Paratrichodorus paraallius, Decraemer & Archidona-Yuste & Clavero-Camacho & Vovlas & Cantalapiedra-Navarrete & Alba & Ruiz-Cuenca & Castillo & Juan & Palomares-Rius, 2024

Decraemer, Wilfrida, Archidona-Yuste, Antonio, Clavero-Camacho, Ilenia, Vovlas, Alessio, Cantalapiedra-Navarrete, Carolina, Alba, Ruiz-Cuenca, Castillo, Pablo, Juan & Palomares-Rius, 2024, Unravelling cryptic diversity in the Paratrichodorus allius- group species complex to resolve eight new species of the genus and new insights on the molecular phylogeny % Nematoda: Trichodoridae), Zoological Journal of the Linnean Society 202 (3), pp. 1-44 : 31-34

Paratrichodorus paraallius sp. nov. Decraemer et al.

( Figs 3K, L , 16 , 17 ; Table 9 )

Zoobank registration: urn:lsid:zoobank.org:act:0FC78198-4409-4407-A1F1-1F63AC86050B

Type material: Holotype. Female extracted from soil samples collected from the rhizosphere of wild olive ( Olea europaea subsp. sylvestris ) at Medina Sidonia, Cádiz province, southern Spain (36°19 ʹ 56.3 ʹʹ N latitude, 5°51 ʹ 16.8 ʹʹ W longitude) by J. Martín Barbarroja and G. León Ropero, mounted in pure glycerine and deposited in the nematode collection of Ghent University, Ghent, Belgium (slide number UGMD 104471 ).

Paratypes: Female paratypes extracted from soil samples collected from the rhizosphere of wild olive at Medina Sidonia , Cádiz province , southern Spain, were deposited in the following nematode collections: Ghent University, Ghent, Belgium (slide numbers females paratype UGMD 104470-104471 ); and one female paratype at the USDA Nematode Collection, Beltsville, MD, USA (collection number T-8022p ).

Additional material examined: An additional population was collected also in the rhizosphere of cultivated olive ( Olea europaea ssp. europaea ) at Espiel, Córdoba province, Spain (38°06 ʹ 28.5 ʹʹ N latitude, 5°04 ʹ 19.5 ʹʹ W longitude); unfortunately the specimens of this population were not in good conditions for light microscopic study, and were identified only molecularly.

Etymology: The species epithet refers to Gr. prep. para, alongside of, resembling; N.L. masc. n. allius , because of its close resemblance to Paratrichodorus allius .

Description of female: Body medium-sized (average about 800 µm), cigar-shaped, anteriorly tapered; cuticle non-swollen (2 µm) at midbody; lip region rounded, with protruding double papillae (four cephalic and two subdorsal and two subventral outer labial papillae). Onchiostyle medium-sized (average 47 µm long). Pharynx with a short, narrower part (isthmus) and a pronounced dorsal overlap (11–23 µm) by the intestine, with or without a short ventral overlap (average 6µm) of the ventrosublateral pharyngeal glands; posterior ventrosublateral gland nuclei and dorsal gland nucleus well separated. Cardia obscure. Rectum nearly vertical with anus subterminal. Nerve ring surrounding isthmus; SE-pore at level of posterior end isthmus or anterior part pharyngeal bulb. Reproductive system didelphic-amphidelphic with both branches more or less equally developed; oviduct cells finely granular, connection with reflexed anterior end of ovary not clear but sperm observed near tip reflexed ovary or sperm absent. Vagina short (average 20% of corresponding body width long), barrel-shaped to slight trapezoidal with minor midway indentation at level of vaginal constrictor muscles; pars refringens vaginae in optical section with short (1.5–2.0 µm) oval to rounded triangular sclerotized pieces, nearly parallel to slightly obliquely oriented, about 2.5 µm apart (average); vulva situated on average 58% of body length from anterior end and a longitudinal slit in ventral view. No sublateral/ subventral body pores observed. Tail minute, terminal cuticle not thickened; a pair of terminal caudal pores present.

Male: Unknown.

Code oithin the tabular identification key (based on: Decraemer and Baujard 1998): For female: A222, B22, C1, D1, E23, F34, G3, H2(8), I1, J9, K2, L3, M1, N3, O55, P2, Q4, R2, S1, T1.

Diagnosis and relationships: Paratrichodorus paraallius sp. nov. is characterized by a body medium-sized (average about 800 µm), no males observed. Onchiostyle 47 µm (average) and without reserve onchium in adult; pharyngo-intestinal junction with pronounced dorsal overlap by intestine with or without short ventral overlap by pharynx; SE pore near anterior end pharyngeal bulb; small oval sperm cells observed close to germinal zone reflexed ovary or absent; no sperm in uterus. Vagina short (20% of corresponding body width), barrel-shaped to slightly trapezoid with slight midway indentation at level of vaginal constrictor muscle; pars refringens vaginae in optical section with short (1.5–2.0 µm) oval to rounded triangular sclerotized pieces, nearly parallel to slightly obliquely oriented, 2.5 µm apart (average). No sublateral or subventral body pores observed.

Based upon the tabular identification keys for females (Decraemer and Baujard 1998), sorting on primary features D and C, followed by L and K, resulted in a classification in subgroup 1-12 of group 1. Further sorting on feature P (type of sperm cell), feature N (presence of males), and feature O (location of sperm) groups P. paraallius sp. nov. with P. allius . The new species can hardly be differentiated based on morphological features in female because of the variation in vaginal structures but agrees in males being absent vs. absent or rare in P. allius and in absence of sperm in the uteri but did not show accumulation of sperm in ovarial sac but in the ovary near the germinal zone, a feature also observed in P. allius (Sturhan 1989 ). Definitely, P. paraallius sp. nov. is almost undistinguishable morphologically from P. allius , being described here as separate new species, based on the additional support given by molecular analyses (see below).

Figures

Figure 3. Line drawings for comparison of vagina in the Paratrichodorus allius species-complex group. A* B* P. uliaensis sp.nov.; C* D. P. benalupensis sp. nov.; E* P.hinogerus sp. nov.; F* G* P.tarifaensis sp. nov.; H* P.asidonaensis sp.nov.; I* P. rocianerus sp. nov.; J* P.litoralis sp. nov.; K* L* P. paraallius sp. nov.; M–P* P.allius based on Sturhan %1989); Q* P.allius* paratype; R* S* P.teres* paratypes.

Figure 16. Line drawings of Paratrichodorus paraallius sp. nov.. Female. A* pharyngeal region* holotype. B* pharyngeal region* paratype. C* anterior genital branch* paratype. D* tail region* holotype.E* vagina region* holotype. Scale bar = 10 µm.

Figure 17. Light micrographs of Paratrichodorus paraallius sp. nov.. Holotype female. A* total view. B* pharyngeal region.G* vagina region. H* tail region. Paratype females.C* posterior pharyngeal region. D* ovary anterior genital branch* arrow indicates sperm near ovary tip. E-F.Vagina region. Scale bars A = 100 µm; B–D = 20 µm; E–H = 10 µm.