Pseudodesmus ngoclinh, Nguyen & Nguyen & Korsós, 2024

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, Zoosystematics and Evolution 100 (4), pp. 1515-1541 : 1515-1541

Pseudodesmus ngoclinh sp. nov.

Figs 6 , 7 , 8 , 9 , 10

Material examined.

Holotype. Vietnam • 1 male; Kon Tum Province, Ngoc Linh Mts ; 15.07134 ° N, 107.97158 ° E; 1,800–1,900 m a. s. l.; 21 Mar. – 9 Apr. 2006; Anh D. Nguyen leg.; primary forest, decaying wood, under the bark; IEBR-Myr 986 H .

Paratypes. Vietnam • 1 male, 2 females; same data as for the holotype; IEBR-Myr 986 P • 2 females; same data as for the holotype; HNHM .

Diagnosis.

Head slightly broader than collum. Collum with distinct paraterga directed anterad, with two rows of 1 + 1 smaller and 2 + 2 larger tubercles. Body covered with dense minute pubescence. Midbody body rings with two rows of tubercles on metazona, posterior row of 4–5 + 4 – 5 tubercles, shorter and extending to base of paraterga; anterior row of 5–10 + 5–10 small tubercles, longer, extending to about midlength of paraterga. Posterior gonopods 6 - segmented, with two apical stylets.

Diagnosis remarks.

The new species is easily distinguished from P. camptotrichus by coloration (yellowish / brownish plus dark spots vs whole earth brown). It also differs from P. variegatus and P. camptotrichus in having smaller size (length: 11.4 mm vs 32 mm and 14 mm; width: 2.74 mm vs 5.8 mm and 2.0 mm, respestively), number of metazonal tubercles (two rows of 5–10 + 5–10 and 4–5 + 4 – 5 vs two rows of 8–15 + 8 – 15 and 5–7 + 5 – 7, and two rows of 6 + 6 to 9 + 9 each row, respectively).

Description.

Male holotype.

Measurements: 51 body rings plus telson; length about 11.40 mm, length of midbody metazona about 0.19 mm, width of midbody metazona about 2.74 mm, width of midbody prozona about 1.26 mm; ratio of width of head and width of collum = 1.05.

Coloration of ethanol-preserved specimens: first 6 body rings including collum yellowish in the middle, then most body rings with a light median section, dark spots (on tubercles) irregularly on one side or both sides, dark spots on paraterga, asymmetrically, and almost every body ring different, sometimes repeating 3–4 body rings, last 5–6 body rings uniformly brownish.

Head (Figs 6 A, B, F , 7 A – D ) round-shaped, moderately densely setose. Antenna stout, clavate, in situ reaching to body ring 5; antennomere 6> 5> 3> 4 = 2> 7 = 1 in length. Collum with distinct paraterga directed anterad, with two rows: anterior row with 1 + 1 tubercles, posterior row with 2 + 2 tubercles, paramedian ones being larger (Figs 6 A , 7 A, B ). Body covered with dense minute pubescence. Slopes of dorsum steep, so body in cross-section subtriangular. Body rings 2–4 with a single row, each of 1 + 2, 1 + 1, 3 + 4 tubercles, respectively (Figs 6 A, C , 7 A ). Midbody body rings with two rows of tubercles on metazona, posterior row of 4–5 + 4 – 5 tubercles, shorter and extending to base of paraterga; anterior row of 5–10 + 5–10 small tubercles, longer, extending to about midlength of paraterga. Paramedian tubercles considerably larger, and posterior paramedian tubercles much larger than anterior paramedian ones (Figs 6 D , 8 A , 8 C ). The last 6 body rings with only a row of 4 + 4 tubercles (Figs 6 E , 8 C ).

Paraterga curved strongly anteriad on body rings 2–5, increasingly less so on body rings 6–10 (to body ring 11 on paratype specimens), slightly curved caudad on body ring 11 (to body ring 12 on paratype specimens) and following body rings; caudal curvature of paraterga increasingly clear on 6–7 posteriormost body rings in front of telson; paraterga of penultimate body ring produced strictly caudad and flanking telson (Figs 6 E, G , 8 C, D ). Caudal paratergal margins entire, without notches (Figs 6 – 8 ).

Telson (Figs 6 C , 8 C, D ) short, caudal margin rounded; epiproct with 2 + 2 small / tiny tubercles at caudal margin. Paraprocts and hypoproct semi-circular.

Legs slender, shorter than width of body ring together with paraterga, terminating before lateral paratergal margins. Prefemur = tarsus> femur> postfemur = tibia in length. Claws normal. Coxal sacs present on body rings 3–41 (Figs 6 G , 8 B ).

Gonopods: Two pairs of gonopods directed mesoanteriad. Anterior gonopods (Figs 9 A , 10 A, B ) 6 - segmented, covered with long setae; coxite broadly stout, 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 9 B , 10 C, D ) 6 - segmented, covered with sparse long setae; coxite broad, basal part sparsely covered with microgranulations; podomeres 2–5 short and stout; ultimate podomere (po 6) longest, with two apical stylets (sty).

Variation.

Male paratype: 53 body rings + telson; length about 11.73 mm, length of midbody metazona about 0.21 mm, width of midbody metazona about 2.79 mm, width of midbody prozona about 1.28 mm.

Female paratypes. 48–51 body rings + telson. Length ca 12.21–13.52 mm, width of midbody metazona about 2.84–3.02 mm; width of prozona about 1.32 mm; length of metazona about 0.26 mm, average ratio of width of head and width of collum = 1.14. Nonsexual characters as in male.

Etymology.

Named after the “ Ngoc Linh ” Mountain, the type locality. Noun in apposition.

Distribution.

The species has been found in Ngoc Linh Mts at the high elevation of 1800–1900 m a. s. l. in Kon Tum Province, Vietnam.

DNA barcoding.

A fragment of the COI gene is accessioned at NCBI GenBank with the following accession numbers: PQ 423222 – PQ 423223. The new species has a COI gene similarity with Andrognathidae spp. ( MF 983566 and MF 983567 ) of 89.13 % and 89.37 % identity, respectively.

Figures

Figure 6. Pseudodesmus ngoclinh sp. nov, holotype (IEBR-Myr 986 H), under white light. A – C. Anterior part of body, dorsal view (A, C), ventral view (B); D. Midbody body rings, ventral view; E. Posterior part of body dorsal view; F. Anterior half of body, ventral view; G. Posterior half of body, ventral view. Scale bars: 1 mm.

Figure 7. Pseudodesmus ngoclinh sp. nov, holotype (IEBR-Myr 986 H), under UV light. A. Anterior part of body, dorsal view; B. Head and collum, anterior view; C. Anterior half of body, ventral view; D. Anterior part of body, ventral view. Scale bars: 1 mm.

Figure 8. Pseudodesmus ngoclinh sp. nov, holotype (IEBR-Myr 986 H), under UV light. A, B. Midbody body rings, dorsal view (A), ventral view (B); C, D. Posterior half of body, dorsal view (C), ventral view (D). Scale bars: 1 mm.

Figure 9. Pseudodesmus ngoclinh sp. nov, holotype (IEBR-Myr 986 H), gonopods. A. Left anterior gonopod, ventral view; B. Posterior gonopods, anterior view. Abbreviations: co = coxite = podomere 1; po 2 = podomere 2; po 3 = podomere 3; po 4 = podomere 4; po 5 = podomere 5; po 6 = podomere 6 (ultimate podomere); mse = macrosetae; sty = stylet. Scale bars: 0.1 mm.

Figure 10. Pseudodesmus ngoclinh sp. nov, holotype (IEBR-Myr 986 H), gonopods. SEM. A, B. Left anterior gonopod, ventral view (A), posterior view (B); C, D. Posterior gonopods, ventral view (C), anterior view (B). Abbreviations: co = coxite = podomere 1; po 2 = podomere 2; po 3 = podomere 3; po 4 = podomere 4; po 5 = podomere 5; po 6 = podomere 6 (ultimate podomere); mse = macrosetae; sty = stylet.