Zephronia panhai, 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 panhai sp. nov.

Figures 2E, F ; 11 ; 12 ; 13G, H ; 14D, E

Type material.

Holotype: Thailand • ♂; Phetchaburi Province, Tha Yang District, Wat Khao Khachiu; 12°57'42.7"N, 99°54'49.9"E; 22 m a.s.l.; 17 August 2019; R. Srisonchai, C. Sutcharit, W. Siriwut leg.; CUMZ-Zeph0009. Paratypes: Thailand - Phetchaburi Province • 8 ♂♂ 6 ♀♀; same locality as holotype; CUMZ-Zeph0010 • 1 ♂; same data as holotype; NHMD • 1 ♂; same data as holotype; ZMUM • 1 ♂; same data as holotype; ZRC. Further specimens, not paratypes: Thailand - Phetchaburi Province • 3 ♂♂ 2 ♀♀; Khao Yoi District, Wat Puangmali (Wat Tham Khao Ego); 13°18'45.3"N, 99°47'5.1"E; 22 m a.s.l.; 8 September 2016; R. Srisonchai, C. Sutcharit, W. Siriwut leg.; CUMZ-Zeph0010 • 1 ♂ 2 ♀♀; Rachaburi Province, Pak Tho District, Wat Buri Ratchawanaram; 13°22'45"N, 99°47'6"E, 26 m a.s.l.; 14 November 2019; R. Srisonchai, C. Sutcharit, W. Siriwut leg.; CUMZ-Zeph0010 • 2 ♂♂ 4 ♀♀; Kanchaburi Province, Mueang District, Wat Tham Mangkorn Thong; 13°59'8.2"N, 99°31'2.9"E; 46 m a.s.l.; 3 September 2017; R. Srisonchai, C. Sutcharit, W. Siriwut leg.; CUMZ-Zeph0010.

Etymology.

The species name recognizes the great professor and a long-time mentor to the authors, Somsak Panha (Chulalongkorn University Museum of Zoology, Thailand).

Diagnosis.

Differs from all congeners by the combination of the following characters; grey body color, adult body length ca. 21 mm, tergites covered by conspicuous setae, long setae on tergites extending over the posterior margin (Figs 13G , 14D ), marginal bristles of endotergum not extending over posterior margin, margin of operculum on vulva slightly concave and slightly invaginated medially, telopoditomere 3 of anterior telopods with conspicuous crenulated teeth and telopoditomere 3 of posterior telopods with a row of 11or 12 crenulated teeth.

Description.

Body length: Length in male 19.0-22.0 mm (holotype 20.0 mm), female 20.0-23.0 mm; head 4.0 mm; thoracic shield 4.0-4.5 mm; anal shield 6.0-7.5 mm.

Body width: Width in male 10.0-11.5 mm (holotype 10.0 mm), female 10.0-12.0 mm; head 6.0-7.0 mm; thoracic shield 10.0-11.0 mm; anal shield 9.5-10.5 mm.

Body height: Height in male 7.0-7.5 mm (holotype 7.0 mm), female 7.0-7.5 mm; thoracic shield 6.0-7.0 mm; tergite 6.5-7.5 mm.

Color (Fig. 2E, F ): Specimens in life with light grey; head, antennae and collum greenish grey; thoracic shield, tergites and anterior part of anal shield grey; paratergites, posterior margins of tergites and posterior part of anal shield greyish brown. Color in alcohol after two years not changed.

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. 70 ommatidia. Aberrant ocellus located near antennal groove (at upper part of groove).

Antenna (Fig. 11A ): Short and stout, with rounded joints; length ca. 3 mm; reaching backward to tarsus of leg 2. 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 ca. 50 apical cones. No sclerotized ridge between antennal socket and ommatidia.

Tömösváry’s organ: Separated from ommatidia, located on a brim between ommatidia and antennal socket, smaller in diameter than an individual ocellus.

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

Stigmatic plates (Fig. 11C ): First stigmatic plate subtriangular; apex rounded, broad; straight towards coxa 1.

Laterotergites : Laterotergites 1 and 2 narrow, projecting to a sharp tip.

Collum: Surface with very long setae in both anterior and posterior margins, setae located in pits.

Thoracic shield: Surface as those of tergites, covered with tiny setae; shallow groove with long setae, slightly broad at anterolateral margin.

Tergites (Fig. 2E, F ): Quite dull; surface densely setose, easily seen by normal vision; with numerous and short setae, each locating in tiny pits; tips of paratergites of midbody tergites weakly curved, directed posteroventrad.

Endotergum (Figs 13G, H , 14D, E ): Posterior margin flat, regular; tip of setae. Inner section (inner area) with a few setiferous tubercles or setae. Middle section (middle area) with a single row of conspicuous, elliptical cuticular impressions; distance between impressions longer than individual diameter. Bristles arranged in two rows, tip of the longest bristles not extended beyond posterior margin or not reaching to posterior margin.

Anal shield: Sexually dimorphic, in female weakly bell-shaped, in male strongly bell-shaped. Outer surface pubescent, setae small and very short, similar to those of tergites. Inner surface (underside) covered by setae; with a single locking carina, half as long as length of last laterotergite.

Legs (Fig. 11B ): Leg-pairs 1 and 2 without an apical spine. Leg-pair 1 with two or three ventral spines, leg-pair 2 with four ventral spines. Leg-pair 3 with six ventral spines and one apical spine. Leg-pair 4 with 7-9 ventral spines and 1-3 apical spines. Leg-pairs 5-19 with 7-11 ventral spines and 1-3 apical spines. Last two leg-pairs with eight or nine ventral spines and one or two apical spines. In leg 9, femur 1.4 ×, tarsus 3.5 × 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 quite short and stout, slightly extended mesally; mesal margin with 7 or 8 conspicuous teeth, long, conical shape.

Subanal plate (Fig. 11F ): Trapeziform, undivided; central margin (tip) slightly rounded, narrow; lateral margin slightly concave. Densely setose.

Male sexual characters (Fig. 11D ): Gonopore large, covered with a single, undivided, triangular, sclerotized plate.

Anterior telopods (Fig. 12A, B, D ): Telopodite with four telopoditomeres; telopoditomeres 3 and 4 clearly divided by a conspicuous suture; all telopoditomeres sparsely setose, except for telopoditomeres 4 without setae. First telopoditomere rectangular, broad, 1.5 × longer than wide. Telopoditomere 2 stout. Process of telopoditomere 2 quite short, subequal in length to telopoditomeres 3; visible in posterior view, but partly seen mesally in anterior view; tip curved and well-rounded, directed mesad, close to basal part of telopoditomere 4. Margin towards telopoditomere 3 with a membranous area carrying a sclerotized process (sp); a process conspicuous, but very short, tip quite sharp. Telopoditomere 3 with three crenulated teeth (cr-T), conspicuous. Telopoditomere 4 very short and stout, conspicuous; tip round, directed mesad; with two small, sclerotized spines in posterior side.

Posterior telopods (Fig. 12A, C, D ): Telopodite with four telopoditomeres; telopoditomeres 1 and 2 on both sides with sparse setae, 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 stout and narrow, ca. half as long as telopoditomere 2. 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, strongly curved, tip directed anteroventrad; at margin with several conspicuous semi-circular rows of sclerotized spots. Margin towards movable finger with two membranous lobes, conspicuous long, triangular, inner lobe bigger and longer than outer one, tip sharp. Telopoditomere 3 very long and slender, tapering apically, 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 11-12 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 mesad.

Female sexual characters (Fig. 11E ): Vulva large, covering ca. 2/3 coxa, located at mesal side, extending mesally to basal third of prefemur. Operculum regularly rounded, margin slightly concave, mesal margin not protruding.

Distribution and habitats

(Fig. 16 ). The new species is known from Phetchaburi, Ratchaburi, and Kanchanaburi provinces. All specimens were collected from limestone habitats.

Remarks.

At the field collecting site, grey living specimens blended in perfectly with the brownish grey rock or leaf litter, making it difficult to find the animals. All specimens were infested by tiny, engorged, white, phoretic deutonymphs of an unidentified mite. The mite can often be found especially on the ventral part of the body such as antennal sockets and coxae, and could easily be discerned. The distribution of Z. viridescens from Dawei, Myanmar (Tavoy, Lower Burma - Moti Ram), is quite close to where the new species is distributed. However, Z. panhai sp. nov. differs from it by having a shorter body length ca. 21 mm (vs. longer, ca. 32 mm) and telopoditomeres 3 and 4 of anterior telopod distinctly separated (vs. indistinctly separated).

Unconfirmed species recorded for Thailand

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 11. Zephronia panhai sp. nov. A-D male holotype (CUMZ-Zeph 0009) E, F female paratypes (CUMZ-Zeph 0010) 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 12.. Zephronia panhai sp. nov., male holotype (CUMZ-Zeph 0009) 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, sp = sclerotized process, 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.