Pseudodesmus karstomus Nguyen, Nguyen & Korsós, 2024, sp. nov.
Creators: name: Nguyen, Anh D.
name: Nguyen, Lien T. P.
name: Korsós, Zoltán
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Platydesmida
Andrognathidae
Pseudodesmus
Pseudodesmus karstomus

description: Pseudodesmus karstomus sp. nov.
Figs 11, 12, 13, 14
Material examined.
Holotype. Vietnam • 1 male; Cao Bang Province, Tra Linh District, Quoc Toan commune, Thang Hen Lake, near Ham Huong cave; 22.7588 ° N, 106.2958 ° E, 1 Nov. 2021; A. D. Nguyen leg.; IEBR-Myr 959 H.
Paratypes. Vietnam • 1 male, 1 female same data as for the holotype; IEBR-Myr 959 P • 1 male; same data as for the holotype; HNHM.
Diagnosis.
Terga and base of paraterga marbled yellowish brown with some blackish tubercles on several body rings. Head triangular-shaped, slightly narrower than collum. Collum stout strongly bilobed, anteriorly excavated, with small 2 bumps in the middle, densely setose. Midbody metazonae with two rows of tubercles, anterior row with 7–8 + 7 – 8 tubercles, posterior one with 2 + 2 tubercles. Posterior gonopods 6 - segmented, with two apical stylets and two lateroapical stylets.
Diagnosis remarks.
The new species is easily distinguished from P. camptotrichus by coloration (marbled yellowish brown with some blackish tubercles vs earth brown), larger size (length: 18.64 mm vs 14 mm; width: 2.74 mm vs 2.0 mm), number of metazonal tubercles (two rows of 7–8 + 7 – 8 and 2 + 2 tubercles vs two rows of 6 + 6 to 9 + 9 each row).
It also differs from P. variegatus in having smaller size (length: 18.64 mm vs 32.0 mm; width: 2.74 mm vs 5.8 mm), number of metazonal tubercles (two rows of 7–8 + 7 – 8 and 2 + 2 tubercles vs two rows of 8–15 + 8 – 15 and 5–7 + 5 – 7).
Pseudodesmus karstomus sp. nov. is differentiated from two above new species, P. bidoup sp. nov. and P. ngoclinh sp. nov in body size and number of gonopod stylets. It shares with P. bidoup sp. nov. a posterior gonopod with four distal stylets, but two species are distinguished by body size (length: 18.62 mm vs 9.25 mm; width: 4.05 mm vs 1.63 mm). Pseudodesmus karstomus is also larger than P. ngoclinh (length: 18.62 mm vs 11.4 mm; width: 4.05 mm vs 2.74 mm), and having more distal stylets in posterior gonopod (four vs two).
Description.
Male holotype.
Measurements: 61 body rings plus telson, length about 18.64 mm, length of midbody metazona ca. 0.29 mm, width of midbody metazona ca. 4.05 mm, width of midbody prozona ca. 1.35 mm; ratio of width of head and width of collum = 0.98.
Coloration of ethanol-preserved specimens: Terga and base of paraterga marbled yellowish brown with some blackish tubercles on several body rings. Collum and first 4 body rings yellow, 5 th weakly brownish, then increasing color pattern: 6–10 th light in the middle and brownish at the base of paraterga, 11–12 th dark brown in the middle and light borwn at the base of paraterga; then the same pattern repeated as 4 light + 3 brown, 5 light + 3 brown, 5 light + 3 brown, 5 light + 3 brown, 3 light + 2 brown, 2 light + 2 light brown, 3 light in the middle and brownish at the base of paraterga, then the ultimate 3 body rings plus telson and light yellow (Fig. 11 A – C). Paraterga paler in preserved specimens, but pinkish in alive specimens.
Head (Figs 11 D, E, 12 D, E) somewhat smooth, triangular-shaped. Antenna short, somewhat stout, in situ extending to body ring 5; antennomere 6> 5> 3> 4 = 2> 7 = 1 in length. Collum (Figs 11 D, E, 12 D, E) stout strongly bilobed, anteriorly excavated, with two small bumps in the middle, densely setose. Paraterga very tiny, somewhat like lateral keels, caudal margin similar lateral keels.
Tergum 2 with a row of 1 + 1 large, subtriangular tubercles, those tubercles reducing to rather small ones on subsequent terga. Terga 2–5 with one row, from 6 th onward with two rows of tubercles, anterior row with 7–8 + 7 – 8 tubercles, reaching the middle of paraterga, posterior row with only 2 + 2, never extending to paraterga; the 1 + 1 median tubercles (both anterior and posterior) transversally enlarged, elongated, oval (Figs 11 A – C, 12 A – C).
Paraterga in general very wide (Figs 11, 12). Paraterga 2–3 (Figs 11 D, E, 12 D, E) anterad directed; paraterga 3–5 extending slightly lateroanterad, paraterga 6–58 laterad, 59–61 lateroposteriad, 62–63 posteriad. Paraterga 1–13 rectangular, from 14 th onwards tapering laterad, anterior edge increasingly bending backwards.
Telson (Figs 11 C, F, 12 C, F) short, caudal margin rounded; epiproct with 3 + 3 setiferous tubercles at caudal margin (Figs 11 C, F, 12 C, F). Paraproct and hypoproct semi-circular (Figs 11 F, 12 F).
Legs slender, shorter than paraterga, terminating before lateral paratergal margins. Claws normal. Coxal sacs present ventrally on body rings 3–59 (Figs 11 F, 12 F).
Gonopods (Figs 13, 14): Two pairs of gonopods directed mesoanteriad. Anterior gonopods (Figs 13 A, 14 A, B, F) 6 - segmented, covered with long setae; coxite (co) broad, basal part sparsely covered with microgranulations; podomeres 2–5, short and stout; podomere 6 slightly longer than other podomeres, distally carrying macrosetae (mse). Posterior gonopods (Figs 13 B, 14 C, D, E) 6 - segmented, covered with sparse long setae; coxite (co) broad, basal part sparsely covered with microgranulations; podomeres 2–5 short and stout; ultimate podomere (po 6) longest, with two apical stylets and two lateroapical stylets (sty).
Variation.
Male paratypes have 62–63 plus telson, length about 17.76–17.92 mm, length of midbody metazoan ca. 0.29–0.33 mm, width of midbody metazona ca. 2.90–2.94 mm, width of midbody prozona ca. 1.37–1.45 mm; average ratio of width of head and width of collum = 0.89 (width of collum: 0.61 mm, width of head: 0.68 mm).
Female paratype. 66 body rings plus telson; length about 22.36 mm, length of midbody metazoan ca. 0.42 mm, width of midbody metazona ca. 4.06 mm, width of midbody prozona ca. 1.75 mm; ratio of width of head and width of collum = 0.9 (width of collum: 0.72 mm, width of head: 0.65 mm). Nonsexual characters as in male.
Etymology.
Named to emphasize the type locality, karst areas. Noun in apposition.
Distribution.
The species was found in limestone mountain in Cao Bang Province, northern Vietnam.
DNA barcoding.
A fragment of the COI gene is accessioned at NCBI GenBank with the following accession numbers: PQ 423224 – PQ 423225. The new species has a close COI gene similarity with Gosodesmus claremontus (JX 962723) of 85.14 % in the BLAST search.
description: Published as part of Nguyen, Anh D., Nguyen, Lien T. P. & Korsós, Zoltán, 2024, A review of the millipede genus Pseudodesmus Pocock, 1887 (Diplopoda, Platydesmida, Andrognathidae) from Vietnam, with descriptions of five new species and notes on its phylogeny, pp. 1515-1541 in Zoosystematics and Evolution 100 (4) on pages 1515-1541, DOI: 10.3897/zse.100.132111