Stauratostoma shelleyi n. gen., n. sp. (Nematoda: Rhabditida: Thelastomatidae) from Appalachian Polydesmid Millipedes (Polydesmida: Xystodesmidae)

Phillips, Gary; Pivar, Robert J.; Sun, Xiocaun; Moulton, John K.; Bernard, Ernest C.

doi:10.21307/jofnem-2018-023

Figures & Tables

Stauratostoma shelleyi n. gen., n. sp. A, Habitus, lateral view. B, Anterior end, lateral view. C, Secretory-excretory system region, ventral view. D, Reproductive system of non-gravid female, right-side lateral view; intestinal detail provided only for anterior and posterior parts. E, Developing reproductive system of presumed fourth-stage juvenile. F, Posterior region of reproductive system of older gravid female, left-side lateral view; only the posterior end of the digestive system is illustrated. G, Posteriormost portion of posterior gonad of younger female with eggs in single file. Scales: A = 200 μm; B, E, F = 50 μm; C, D, G = 100 μm.

Stauratostoma shelleyi n. gen., n. sp., scanning electron microscope. A, Anterior region, sublateral view. B, Enlargement of 2A, showing lateral labial pit or depression (LP), complete dorsal or ventral groove (CG) and sublateral and lateral incomplete grooves. C, Dorsal or ventral view showing complete groove and reticulated surface between lobes and labial disc. D, Labial disc with amphid aperture (AM) and associated spine (SP). Scales: A = 20 μm; B–D = 10 μm.

Stauratostoma shelleyi n. gen., n. sp. A, Head end, lateral view; inset shows accessory spine near amphid aperture. B, Scanning electron microscope of anterior region showing large S–E pore. C, S–E pore with operculum. D, Typical egg, with slightly roughened outer layer. E, Lateral field, esophageal region. F, Lateral field, posterior region. Figures 3E, F are phase-contrast images. Scales: A, D = 20 μm; B, F = 50 μm; C = 10 μm; E = 100 μm.

Fig. 4

Stauratostoma shelleyi n. gen., n. sp. A, B Pebble-like longitudinal subcuticular bands alternating with muscle bands; figures are of same area but imaged at different focus depths. C Annules in profile with pebbly subcuticle. D Annules in profile at a muscle zone, and extensive lattice of fibers in pseudocoel. Scales = 50 μm.

Molecular tree of millipede-parasitic nematodes based on partial 28S rDNA analysis. Stauratostoma shelleyi is shown as the sister group to Thelastoma spp. Posterior probabilities are shown above the nodes and bootstrap values are below the nodes.

Stauratostoma shelleyi n. gen., n. sp., known distribution by county in southeastern United States.

Correlation of nematode length and millipede weight for two Apheloria spp., 95% confidence limits shown.

Genera of xystodesmid millipedes dissected_

Species	Millipedes dissected (n)	Millipedes with Stauratostoma shelleyi	Total S. shelleyi	Mean	Range
Apheloria montana	77	59	269	3.5	0‒19
Apheloria tigana	4	0	0	0	0
Apheloria virginiensis	56	35	276	4.9	0‒31
Boraria deturkiana	1	0	0	0	0
Brachoria initialis	6	4	41	6.8	0‒21
Brachoria ochra	3	2	45	15	0‒32
Cherokia georgiana	47	5	41	0.9	0‒23
Dicellarius talapoosa	2	0	0	0	0
Harpaphe haydeniana	29	0	0	0	0
Pleuroloma cala	56	0	0	0	0
Pleuroloma flavipes	44	0	0	0	0
Sigmoria ainsliei	2	2	20	10	5‒15
Sigmoria aphelorioides	1	0	0	0	0
Sigmoria cheiropus	14	1	6	0.4	0‒6
Sigmoria mimetica	10	2	2	0.2	0‒1
Total	352	110	700	2.8	0‒32

Morphometrics of female Stauratostoma shelleyi n_ gen_, n_ sp_ from Apheloria montana_

		Paratype females (n = 30)
Measurements (µm)	Holotype female	Mean	SD	Range	CV
Length	2,522	2,357	249	1,805‒2,683	10.6
Maximum width	192	178	33.9	98‒237	19.1
First annule width	11.1	10.3	0.89	8.1‒12.3	8.3
Second annule width	8.4	7.8	1.2	5.3‒9.9	14.9
Esophagus length	508	486	50.0	347‒548	10.3
Basal bulb length	116	111	8.6	84‒126	7.8
Head to excretory pore	404	389	43.9	274‒445	11.3
Vulva to anterior head	991	935	105.3	676‒1066	11.3
Anus to anterior head	1,570	1,517	174.1	1,105‒1,715	11.5
Egg length	75.2	74.2	3.4	67.2‒79	4.5
Egg width	48.4	49.1	2.7	43.9‒55.4	5.4
Tail length	952	84.0	90.8	649‒973	10.8
Ratios
a	13.1	13.6	2.2	10.1–18.4	16.5
b	5.0	4.9	0.43	4.3‒5.9	8.9
c	2.6	2.8	0.2	2.4‒3.3	5.5
V	39.3	39.7	2.4	33.2‒44.4	6.1
V′	0.63	0.62	0.03	0.53‒0.69	5.1

Stauratostoma shelleyi n. gen., n. sp. (Nematoda: Rhabditida: Thelastomatidae) from Appalachian Polydesmid Millipedes (Polydesmida: Xystodesmidae)

Figures & Tables

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Genera of xystodesmid millipedes dissected_

Morphometrics of female Stauratostoma shelleyi n_ gen_, n_ sp_ from Apheloria montana_

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