Pseudodesmus irregularis, 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

publication ID	https://doi.org/ 10.3897/zse.100.132111
publication LSID	lsid:zoobank.org:pub:B39508EB-6EB2-4CC0-88D8-B3E87BDCED02
DOI	https://doi.org/10.5281/zenodo.14052233
persistent identifier	https://treatment.plazi.org/id/92A47517-07F1-58C4-99FD-3B94C2D1B998
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Pseudodesmus irregularis
status	sp. nov.

Treatment

Pseudodesmus irregularis sp. nov.

Figs 21 View Figure 21 , 22 View Figure 22 , 23 View Figure 23 , 24 View Figure 24

Material examined.

Holotype. Vietnam • 1 male; Khanh Hoa Province, Hon Ba Mt. ; 12.11124 ° N, 108.98426 ° E; 1,500 m a. s. l.; 15–24 Apr. 2006; A. D. Nguyen leg.; primary forest; IEBR-Myr 958 H . GoogleMaps

Paratypes. Vietnam • 1 male; same data as for holotype; IEBR-Myr 958 P GoogleMaps • 1 female; Kon Tum Province, Ngoc Linh Mt ; 15.07071 ° N, 107.97142 ° E; 1,700 m a. s. l.; 25 Mar. – 11 Apr. 2004, A. D. Nguyen leg.; regenerated forest; IEBR-Myr 960 GoogleMaps .

Diagnosis.

Head narrower than collum. Collum bilobed, caudal margin highly elevated with 3 + 3 tubercles with 3 + 3 tubercles, and with a row of 1 + 1 tubercles. Midbody ring with 2 distinct rows of tubercles, anterior row of 6–9 + 6 – 9 and posterior of 3 + 3. Paratergal margins with small / tiny dentations or notches. Posterior gonopods 6 - segmented, with three apical stylets.

Diagnosis remarks.

The new species is distinguished from P. camptotrichus by coloration (irregularly yellow with brown spots vs earth brown), shorter length (12.92 mm vs 14 mm), slightly wider (2.39 mm vs 2.0 mm), having less number of tubercles in posterior metazonal row (3 + 3 vs 6–9 + 6 – 9). The new species is similar to P. variegatus regarding body coloration (irregularly yellow with brown spots), but two species can be separated by body size (length: 12.96 mm vs 32 mm; width: 2.39 mm vs 5.8 mm) and and number of metazonal tubercles (two rows of 6–9 + 6 – 9 and 3 + 3 vs two rows of 8–15 + 8 – 15 and 5–7 + 5 – 7).

Pseudodesmus irregularis sp. nov. is differentiated from above four new species, P. bidoup sp. nov., P. ngoclinh sp. nov, P. karstomus sp. nov. and P. condao sp. nov. in body coloration of irregularly yellow with brown spots, body size and number of stylets (three vs four, two, four, and two, respectively).

Description.

Male holotype.

Measurements: 42 body rings plus telson, length about 12.96 mm, length of midbody metazona 0.24 mm, width of midbody metazona 2.39 mm, width of midbody prozona 1.08 mm; ratio of width of head and width of collum = 0.74.

Coloration of ethanol-preserved specimens (Fig. 20 View Figure 20 ): complex and irregular: body rings 1–4 with none, body rings 5–7 with 2 brown spots, body ring 8 brown on the right, body ring 9 with two brown spots, body ring 10 brown on the right, body ring 11 brown on the left, body rings 12–13 with two brown spots, body ring 14 none, body ring 15 brown on the left, body rings 16–17 brown on the right, body ring 18 brown on left half, body ring 19 brown on right half, body ring 20 brown on left half, body ring 21 none, body ring 22 with left spot, body ring 23 with two brown spots, body rings 24–26 brown on left half, body rings 27–28 full dark, body ring 29 none, body rings 30–32 brown left, body rings 33–34 brown right, body rings 35–36 full, body rings 37–38 none, body ring 39 brown right, body rings 40–42 light brown.

Head (Figs 21 B View Figure 21 , 22 B View Figure 22 ) narrower than collum in width, smooth, round-shaped. Antenna stout, clavate, in situ extending to body ring 6; antennomere 6> 5> 3> 4 = 2> 7 = 1 in length (Figs 21 B View Figure 21 , 22 B View Figure 22 ). Collum (Figs 21 B View Figure 21 , 22 B View Figure 22 ) bilobuled, caudal margin highly elevated with 3 + 3 tubercles, and with a row of 1 + 1 tubercles, paramedian one much larger than lateral one.

Body (Figs 21 View Figure 21 , 22 View Figure 22 ): ring 2 with two rows of 3 + 3 and 1 + 1 tubercles; ring 3 with two rows of 3 + 3 and 3 + 3 tubercles; other rings with 2 distinct rows of tubercles, anterior row of 6 + 6 (increasing to (9 + 9) on midbody rings), and posterior of 2 + 4 (body ring 4), 3 + 3 (ring 5), 3 + 2 (ring 6), 3 + 3 (on other rings). The last 5 rings with two rows of 3 + 3 and 3 + 3 tubercles (Fig. 22 E View Figure 22 ). Anterior rows extending to 2 / 3 paraterga. Paramedian tubercles on posterior rows much larger than ones on anterior rows.

Paraterga well developed, slightly curved anteriad on body rings 2–3, lateral margins smooth (Figs 21 A, B View Figure 21 , 22 A, B View Figure 22 ); increasingly less so on the following body rings, slightly curved caudad on body rings 25–27, and strongly curved caudad on body rings 37–40; paraterga of penultimate body ring produced strictly caudad and flanking telson (Figs 21 E, F View Figure 21 , 22 E, F View Figure 22 ). Lateral margin of paraterga with small / tiny dentations or notches (Figs 21 View Figure 21 , 22 View Figure 22 ).

Telson (Figs 21 E, F View Figure 21 , 22 E, F View Figure 22 ) short, caudal margin rounded; epiproct with 2 + 2 small / tiny tubercles at caudal margin. Paraprocts and hypoproct semi-circular.

Legs slender, shorter than body ring width together with paraterga, terminating before lateral paratergal margins. Claws normal. Coxal sacs strong, present on body rings 3–32 (Fig. 22 F View Figure 22 ).

Gonopods (Figs 23 View Figure 23 , 24 View Figure 24 ): Two pairs of gonopods directed anteriad. Anterior gonopods (Figs 23 A View Figure 23 , 24 A – C View Figure 24 ) 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 23 B View Figure 23 , 24 D – F View Figure 24 ) 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 three apical stylets (sty).

Variation.

Male paratype ( IEBR-Myr 958 P): 36 body rings plus telson, length about 9.75 mm, length of midbody metazoan ca. 0.14 mm, width of midbody metazona ca. 1.72 mm, width of midbody prozona ca. 0.82 mm; ratio of width of head and width of collum = 0.85.

The female from Ngoc Linh Mts ( IEBR-Myr 960 ) has 41 body rings plus telson; midbody width 2.1 mm, length about 10.11 mm. Coloration with widening pattern repeated between 7–12, 13–17, 18–24, 25–31, 32–36 body rings (see also Enghoff 2011). Tubercles are small: on collum only one row, on 2–4 two weak rows (reaching only one row on paraterga), from body ring 5 onwards two rows, each 1 + 1 large tubercles in the middle, then anterior row 10–13 small tubercles reaching edge of paraterga, in posterior row only 3–4 small tubercles, on the last five body rings anterior row is weaker but still with 8–10 small tubercles, in posterior row the median tubercles larger, with 4 small tubercles laterally.

Etymology.

To emphasize the irregular pattern of terga. Noun in apposition.

Distribution.

The species has been only known from Khanh Hoa and Kon Tum Province, southcentral Vietnam.

DNA barcoding.

Sequencing a fragment of the COI gene failed.