Zephronia golovatchi, Srisonchai & Sutcharit & Likhitrakarn, 2021

Srisonchai, Ruttapon, Sutcharit, Chirasak & Likhitrakarn, Natdanai, 2021, The giant pill-millipede genus Zephronia Gray, 1832 from Thailand, with a redescription of Z. siamensis Hirst, 1907 and descriptions of three new species (Diplopoda, Sphaerotheriida, Zephroniidae), ZooKeys 1067, pp. 19-56 : 19

Zephronia golovatchi sp. nov.

Figures 2C, D ; 9 ; 10 ; 13E, F ; 14C

Type material.

Holotype: Thailand - Nakhon Ratchasima Province • ♂; Pak Chong District, Khao Yai National Park, Khao Luk Chang; 14°31'49.6"N, 101°21'32"E; 410 m a.s.l.; 26 April 2009; N. Likhitrakarn, C. Sutcharit, W. Siriwut leg.; CUMZ-Zeph0007. Paratypes: Thailand - Nakhon Ratchasima Province • 1 ♂ 4 ♀♀; same locality as holotype; CUMZ-Zeph0008.

Etymology.

The species is named for our highly esteemed colleague Sergei I. Golovatch (Zoological Museum, State University of Moscow, Russia), one of the most productive millipede taxonomists, who encouraged all new and young myriapodologists in Thailand.

Diagnosis.

Adult body length medium to large> 29 mm, usually 35 mm, up to 37 mm; body brown or dark brown, marginal bristles of endotergum extending over posterior margin, inner surface (underside) of anal shield with a single locking carina on each side, and leg-pair 2 of male coxa with membranous lobe at mesal margin. Similar in these respects to Z. enghoffi sp. nov., but differs from this species by the following combination of characters: antenna long; operculum of vulva regularly rounded and broad in posterior view; mesal margin of operculum not tapering apically; central margin (tip) of subanal plate divided by a conspicuous mesal constriction, process of telopoditomere 2 of anterior telopods shorter than telopoditomere 3; telopoditomere 3 of anterior telopods with 2 or 3 crenulated teeth; immovable finger telopoditomere 2 of posterior telopod (process of telopoditomere 2) shorter than movable finger (consisting of telopoditomeres 3 and 4).

Description.

Body length: Length in male 35.0-36.5 mm (holotype 35.0 mm), female 35.0-37.0 mm; head 5.5-7.5 mm; thoracic shield 5.0-6.0 mm; anal shield 10.5-11.5 mm.

Body width: Width in male 19.0-21.0 mm (holotype 20.0 mm), female 19.0-22.0 mm; head 10.0-11.0 mm; thoracic shield 17.5-20.5 mm; anal shield 16.0-18.5 mm.

Body height: Height in male ca 11.0 mm (holotype 11.0 mm), female 11.0-12.0 mm; thoracic shield 9.0-10.5 mm; tergite 10.0-11.5 mm.

Color (Fig. 2C, D ): Specimens in life with brown color; antennae dark brown; head, collum, thoracic shield, tergites, paratergites, anal shield and legs brown; posterior margin of tergites dark brown. Color in alcohol after 13 years changed to pale brown.

Head: Wide and stout, subtrapeziform; anterior part of head with dense and long setae; central part of head with sparse and long setae; posterior part of head with dense and short setae. Labrum with a single tooth at anterior margin. Each eye with ca. 90-100 ommatidia. Aberrant ocellus located inside antennal groove (at upper part of groove).

Antenna (Fig. 9A ): Quite long and stout, with rounded joints; length ca. 5 mm; reaching backward to tarsus of legs 3 or 4. Lengths of antennomeres 6> 5 = 4 = 3 = 2 = 1. Antennomere 6 densely setose, sensilla basiconica surrounding apical disc. Last antennomere thickened and flattened, strongly widened apically, axe-shaped. Shape of antennae sexually dimorphic; thickened, widened apically and slightly flattened in male, in female cylindrical. Apical disc with 90-100 apical cones. No sclerotized ridge between antennal socket and ommatidia.

Tömösváry’s organ: Not distinctly separated from ommatidium, located closely to anterior margin of ommatidia, equal in size to an individual ommatidium.

Gnathochilarium: Ventral surface with setae, other structures typical of the order. Mandibles not dissected.

Stigmatic plates (Fig. 9C ): First stigmatic plate subtriangular; apex rounded, broad; slightly projecting towards coxa 1.

Laterotergites : Laterotergite 1 narrow, projecting into a sharp tip. Laterotergite 2 broader than laterotergite 1, tip slightly extended, with round projection.

Collum: Surface glabrous, except for anterior margins near rim with isolated and long setae.

Thoracic shield: Surface as those of tergites, covered with inconspicuous and small setae, each seta located in tiny pits; shallow groove wide anterolaterally, with very long setae.

Tergites (Fig. 2C, D ): Quite dull; surface entirely covered by short setae, visible by normal vision; each seta locating in tiny pits; anterior margin densely setose; posterior margin sparsely setose; tip of paratergite in midbody slightly curved, directed posteroventrad.

Endotergum (Figs 13E, F , 14C ): Posterior margin flat, regular. Inner section (inner area) with a few setiferous tubercles or setae. Middle section (middle area) with a single row of small, conspicuous, elliptical cuticular impressions; distance between impressions longer than individual diameter; with a row of conspicuous ridges between bristles and impressions. Bristles arranged in two rows, tip of the longest bristles extended beyond posterior margin or reaching to posterior margin.

Anal shield: Sexually dimorphic, in female very large and weakly bell-shaped, in male slightly bell-shaped. Outer surface pubescent, similar to those of tergites; setae small and very short locating in tiny pits; anterior margin densely setose, posterior margin sparsely setose. Inner surface (underside) covered by setae; with a single, black, very long, locking carina, ca. 1/3 as long as length of last laterotergite.

Legs (Fig. 9B ): Leg-pairs 1 and 2 without apical spine. Leg-pair 1 with two ventral spines, leg-pair 2 with four or five ventral spines. Leg-pair 3 with 7-9 ventral spines and one or two apical spines. Leg-pair 4 with 9-11 ventral spines and one or two apical spines. Leg-pairs 5-19 with 8-12 ventral spines and 1-3 apical spines. Last two leg-pairs with 9-11 ventral spines and one or two apical spines. In leg 9, femur ca. 1.7 ×, tarsus ca. 3.2 × longer than wide. Length of tarsus> femur> prefemur> coxa> tibia ≥ postfemur. All podomeres densely setose. Coxa large, with dentate ridge marginally (coxal process). Coxal process absent in leg-pairs 1 and 2. Prefemur without teeth. Femur extended mesally, mesal margin with 7-9 conspicuous teeth.

Subanal plate (Fig. 9F ): Trapeziform, divided by a conspicuous mesal constriction; central margin (tip) strongly concave, narrow; lateral margin straight. Densely setose.

Male sexual characters (Fig. 9D ): Gonopore large, covered with a single, undivided, subsemicircular, sclerotized plate.

Anterior telopods (Fig. 10A, B, D ): Telopodite with four telopoditomeres; telopoditomeres 3 and 4 often clearly divided by conspicuous suture, some specimens inconspicuous; all telopoditomeres sparsely setose, except for process of telopoditomere 2 with no setae. First telopoditomere rectangular, large, stout. Telopoditomere 2 slender. Process of telopoditomere 2 short, shorter than telopoditomeres 3; visible in posterior view; tip curved, blunt and narrow, directed anteromesad, close to middle part of telopoditomere 3. Margin towards telopoditomere 3 with a membranous area carrying a sclerotized process (sp); a process inconspicuous, short, tip quite sharp. Telopoditomere 3 with two or three crenulated teeth (cr-T), conspicuous. Telopoditomere 4 very short and stout, inconspicuous; tip round, directed mesad; with two small, conspicuous, sclerotized spines in posterior side.

Posterior telopods (Fig. 10A, C, D ): Telopodite with four telopoditomeres; telopoditomeres 1 and 2 on both sides sparse setose, except for apical part of immovable finger (process of telopoditomere 2); telopoditomere 3 at base of inner margin with conspicuous setae, but none for outer margin; telopoditomere 4 without setae. First telopoditomere large, wide, as long as wide. Telopoditomere 2 large, immovable finger (process of telopoditomere 2) relatively shorter than movable finger (consisting of telopoditomeres 3 and 4). Immovable finger slender, twice as long as wide, slightly curved, tip directed anteroventrad; at margin with several semi-circular rows of sclerotized spots, conspicuous. Margin towards movable finger with two membranous lobes, conspicuous and long, conical, inner lobe bigger and longer than outer one, tip sharp. Telopoditomere 3 very long and slender, tapering apically, strongly curved, thrice as long as telopoditomere 4; with a long and sclerotized spine located on a large, swollen, membranous lobe; posterior part with a row of 17 or 18 crenulated teeth (cr-T). Telopoditomere 4 slender, 2 × longer than wide; at inner margin with a large, conspicuous, swollen, membranous lobe and with two evident sclerotized spines; tip curving mesodorsad.

Female sexual characters (Fig. 9E ): Vulva large, covering ca. 2/3 coxa, located at mesal side, extending mesally to basal third of prefemur. Operculum regularly rounded, margin straight, mesal margin not protruding.

Distribution and habitats

(Fig. 16 ). Known only from the type locality. All specimens have been taken from limestone habitats and were found walking on top of decayed wood or hiding under leaf litter.

Remarks.

This species has thin membranous lobe on male coxae 2 (Fig. 9D ), but this lobe seems to be shorter than that of Z. enghoffi sp. nov. (Fig. 7D ).

Figures

Figure 2. Photographs of living Zephronia spp. A, B Zephronia enghoffi sp. nov., paratypes (CUMZ-Zeph 0006) C, D Zephronia golovatchi sp. nov., paratypes (CUMZ-Zeph 0008) E, F Zephronia panhai sp. nov., paratypes (CUMZ-Zeph 0010). Photographs not to scale.

Figure 7. Zephronia enghoffi sp. nov. A-D male holotype (CUMZ-Zeph 0005) E, F female paratypes (CUMZ-Zeph 0006) A right antenna, ventral view B the ninth left leg, posterior view C First coxae with stigmatic plates, posterior view D coxae of second legs with gonopores, posterior view E coxae and prefemur of second legs with vulvae, posterior view F subanal plate, ventral view. Abbreviations: cx = coxa, o = operculum, pre = prefemur, syn-cx = syncoxite, st-pl = stigmatic plate.

Figure 9. Zephronia golovatchi sp. nov. A-D male holotype (CUMZ-Zeph 0007) E, F female paratypes (CUMZ-Zeph 0008) A right antenna, ventral view B the ninth left leg, posterior view C first coxae with stigmatic plates, posterior view D coxae of second legs with gonopores, posterior view E coxae and prefemur of second legs with vulvae, posterior view F subanal plate, ventral view. Abbreviations: cx = coxa, o = operculum, pre = prefemur, syn-cx = syncoxite, st-pl = stigmatic plate.

Figure 10. Zephronia golovatchi sp. nov., male holotype (CUMZ-Zeph 0007) A telopods, anterior view B anterior telopod, anterior view C posterior telopod, posterior view D right anterior and posterior telopods, ventral view. Abbreviations: cr-T = crenulated teeth, cx = coxa, ML = membranous lobe, syn-cx = syncoxite.

Figure 13. SEM of endoterga of body ring 7, all from ventral views A, B Zephronia siamensis Hirst, 1907 C, D Zephronia enghoffi sp. nov. E, F Zephronia golovatchi sp. nov. G, H Zephronia panhai sp. nov. Abbreviations: cp = cuticular impression, ms = middle section, is = inner section, os = outer section, pm = posterior margin.

Figure 14. SEM of endoterga in body ring 7, all from ventral views A Zephronia siamensis Hirst, 1907 B Zephronia enghoffi sp. nov. C Zephronia golovatchi sp. nov. D Zephronia panhai sp. nov. E inner area of endotergum in Zephronia panhai sp. nov.

Figure 16. Known distribution of Zephronia spp. in Thailand. Red triangle = Zephronia lannaensis; green circle = Zephronia phrain; blue triangle = Zephronia enghoffi sp. nov.; sky blue square = Zephronia golovatchi sp. nov.; purple circle = Zephronia panhai sp. nov.; yellow diamond = Zephronia siamensis Hirst, 1907; orange square = Zephronia viridisoma.