Nesorthomorpha montana, Nguyen & Tran & Le, 2018, Nguyen & Tran & Le, 2018

Nguyen, Anh D., Tran, Binh T. T. & Le, Minh D., 2018, First record of the millipede genus Nesorthomorpha Jeekel, 1980 in Vietnam with description of a new species (Diplopoda, Polydesmida, Paradoxosomatidae), Zootaxa 4462 (3), pp. 426-434 : 428-431

NeSOrthOMOrpha MOntana n. sp.

( Figs 1–3 )

Material examined. Holotype: male (IEBR-453H) Kon Tum Province, Ngoc Linh Mts. (15°00'¯ 15°18'N, 107°41'¯ 08°01'E), primary forest, 1,900 m a.s.l, 31 March 2004, coll. Anh D . Nguyen. Paratypes: 1 female (IEBR-453P) same date as holotype; 1 male (IEBR-458) same locality, secondary forest, 1,700 m a.s.l., 21 March–9 April 2006, coll. Anh D . Nguyen. Non-types: 3 females (IEBR-Myr 561) Gia Lai Province, Chu Mon Ray National Park , natural forests, 500–750 m a.s.l., 5 Oct. 2005, coll. Mai Phu Quy ; 1 male, 1 female (IEBR-Myr 596) Gia Lai Province, Chu Mom Ray National Park (14°18′¯ 14°38′N, 107°29′¯ 107°47′ E), natural forests, 1,200 m a.s.l., 31 March 2015, leg. Le Xuan Son ; 1 male, 1 female (IEBR-Myr 633) Gia Lai Province, Kon Ka Kinh National Park (14°09′– 14°30′N, 108°16′– 108°28′E), near head office, natural forests, 890 m a.s.l., 21–24 May 2017, coll. Anh D. Nguyen .

Diagnosis. The species differs from its congeners in the following combination of characters. Sternum 5 with two elevated, small, and rounded processes between coxae 4. Both lamina medialis and lamina lateralis of gonopod solenophore unfolded. Lamina medialis with a long spiniform process d in the middle. Tip of gonopod trifid: terminal and subterminal prongs lobed (tp and stp, respectively), middle prong (mp) a tiny denticle.

Description. Based on Holotype (male) IEBR-453H.

Measurements: Holotype ca. 31.2 mm in length; width of midbody pro- and metazonites 2.0 mm and 3.2 mm, respectively. Coloration ( Fig. 1 ): Whole body reddish brown except lateral area of paranota. Calluses, marginal posterior area of metaterga, waist between pro- and metazonite whitish yellow. Sterna, legs, antennae yellowish brown. Distal part of antennomere 6 and whole antennomere 7 blackish brown. Head: ( Figs 1B–C ) Slightly smaller than collum. Clypeolabral region modestly setose. Frons weakly convex, divided in 2 parts by distinct, thin epicranial suture. Antennae ( Figs 1B–C ) long, claviform, reaching body ring 4 laterally. Most antennomeres subequal in length except for the shortest antennomeres, 7 and 1. Tergites: Collum slightly narrower than body ring 2; surface shining and almost smooth, only faintly rugulose on medioposterior area. Collum with 3 rows of setae: 3+ 3 in anterior, 1+ 1 in middle, 1+ 1 in posterior. Body rings 4<3<2=5¯ 17 in width, posteriorly gradually tapering towards telson. Prozonites shining and smooth. Metatergites shining; anterior half faintly rugulose, and posterior half considerably rugose. Metatergites with a row of 2+2 setae on anterior half and another row of 3+3 setiferous knobs near posterior margin. Transverse sulcus present on metaterga 5¯19, reaching base of paranota. Waist between pro- and metaterga narrow, posterior margin beaded. Pleura with dense covering of microgranules. Pleurosternal carinae present as a full crest with a small caudal tooth on body rings 2¯4, thereafter (moving posteriorly) reduced to a small caudal tooth on body rings 5¯9, to a minute denticle on body rings 10¯16, and missing on subsequent body rings. Paranota ( Figs 1A, C, D, E, G ) well developed, subhorizontal: lying about equal to metatergal surface. Caudal corner beak-like and pointed, more protuberant on posterior-most paranota, surpassing posterior contour of metaterga. Calluses thin on poreless paranota, but thicker on pore-bearing paranota. Epiproct ( Figs 1F, H ) long, broadly truncated, dorsoventrally flattened, with two tiny apicolateral tubercles. Epiproct apex with four spinnerets. Hypoproct ( Fig. 1H ) triangular with two distolateral, well-separated, setiferous knobs. Sterna sparsely setose, without modifications except for fifth sternum with two small, broadly rounded, highly elevated ventrad processes between coxae 4 ( Fig. 1I ). Legs: Long and slender, about 1.6X (male), 1.4X (female) longer than midbody height. Tarsal brushes present on leg pairs 1¯27, absent on other legs. Prefemora not swollen. Femora without modifications. Gonopod ( Figs 2–3 ): Coxae cylindrical, half as long as the telopodite; distoventral part sparsely setose. Prefemur densely setose, set off from acropodite by an oblique sulcus laterally. Acropodite long, slender, slightly curved posteroventrad, with an oblique sulcus laterally. Prostatic groove ending in a flagelliform solenomere apically. Both lamina medialis and lamina lateralis unfolded. Lamina medialis with a spiniform process d in the middle. Tip of gonopod trifid: terminal and subterminal prongs lobate (tp and stp, respectively), middle prong (mp) a tiny denticle.

Variation. Measurements. Body length 29.2¯ 31.2 mm (males), 33.1 mm (female); width of midbody pro- and metazona 2.0 mm (male), 2.5 mm (female) and 2.8¯ 3.2 mm (male), 3.8 mm (female), respectively. Coloration: Specimens from Kon Ka Kinh National Park are slightly different from others in coloration: they are almost black except the paranotal calluses and legs are castaneous brown.

Etymology. a Latin word “ montana ”, which means “mountain”, is an adjective to emphasize the mountainous habitats where the types were found.

Genetic distance and phylogenetic relationship. K2P distance between the new species and Orthomorpha species range from 0.143 to 0.163; between the new species and Antheromorpha festiva is 0.261. The distance

between Nesorthomorpha montana n. sp. and other species varies from 0.148 to 0.317. Both ML and BI trees recover a clade that consisted of Orthomorpha species and Nesorthomorpha montana n. sp. with strong ML and BI values (100% bootstrap value and 0.98 posterior probability) ( Fig. 4 ). The genus Antheromorpha is a weakly supported sister species (ML 54%; BI 0.89) to these two genera. Desmoxytes species formed a well-supported clade, and the genera Piccola and Orthomorphoides are sister to the ingroup taxa.

Figures

FIGURE 1. Nesorthomorpha montana n. sp. from holotype (IEBR-453H). Anterior body section, dorsal (A), ventral (B) and lateral vieW (C); midbody section, dorsal vieW (D); posterior body section, dorsal (E), ventral (F) and lateral vieW (G); hypoproct and epiproct, ventral vieW (H); sternum 5th, ventral vieW (I). Images not to scale.

FIGURE 2. Nesorthomorpha montana n. sp. from holotype (IEBR-453H). Left gonopod, mesal vieW (A); distal part of gonopod, mesal vieW (B), mesodorsal vieW (C). Scale bar = 0.5 mm (A), = 0.1 mm (B and C). Notes: tp = terminal prong; stp = subterminal prong; mp = middle prong; d= spiniform process on lamina medialis.

FIGURE 3. Nesorthomorpha montana n. sp. from holotype (IEBR-453H). Left gonopod, lateral vieW (A), mesal vieW (B). Scale bar = 1 mm.

FIGURE 4. Phylogeny based on maximum likelihood and Bayesian inference from a 500 base pair fragment of the 16S rRNA. Scale bar = eXpected substitutions per site. Bootstrap and BI values are shoWn at nodes. Distal part of gonopods of select taXa: Orthomorpha scabra (a); Nesorthomorpha montana n. sp. (b); Antheromorpha festiva (c); Desmoxytes enghoffi (d); Orthomorphoides setosus (e); Piccola odontopyga (f).