Xenobolus carnifex ( Fabricius, 1775 )

Sankaran, Pradeep M. & Sebastian, Pothalil A., 2020, A redescription and a synonym in the South Asian millipede genus Xenobolus Carl, 1919 (Spirobolida, Pachybolidae), Zootaxa 4780 (1), pp. 165-179 : 167-174

Xenobolus carnifex ( Fabricius, 1775)

( Figs 1–9 )

Iulus (recte: Julus ) carnifex Fabricius, 1775: 428 (brief description of the species).

Iulus (sic!) carnifex -- Fabricius, 1781: 530 (brief description of the species).

Julus Carnifex (sic!)-- Linnaeus, 1788: 3019 (brief description of the species).

Julus carnifex -- Fabricius, 1781: 530 (brief description of the species); 1793: 395 (brief description of the species). Olivier, 1792: 416 (brief description of the species). Latreille, 1802: 76 (brief description of the species). Brandt, 1833: 205 (species name mentioned); 1841a: 127 (species name mentioned); 1841c: 121 (species name mentioned). Humbert, 1865: 57 (brief description of the species).

Iulus (sic!) carnifex -- Gervais, 1837: 13 (species name mentioned); 1847: 163 (brief description of the species). Lucas, 1842: 532 (brief description of the species).

Julus (Spirobolus) carnifex -- Brandt, 1841b: 368 (species name mentioned); 1841c: 121 (species name mentioned).

Spirobolus ruficollis Newport, 1844a: 269 (brief description of the species), synonymised by Pocock (1892).

Spirobolus ruficollis -- Newport, 1844b: 13 (species name mentioned). Preudhomme de Borre, 1884: 76 (species name mentioned). Attems, 1914: 355 (species name mentioned).

Iulus ruficollis -- Gervais, 1847: 175 (brief description of the species).

Spirobolus Carnifex (sic!)-- Koch, 1847: 102 (species name mentioned); 1863: 62, plate XXVII, fig. 53a–b (brief description and illustrations of the species).

Spirobolus carnifex -- Karsch, 1881: 79 (species name mentioned). Preudhomme de Borre, 1884: 73 (species name mentioned). Tömösváry, 1885: 69 (species name mentioned). Daday, 1889: 129 (species name mentioned). Pocock, 1892: 166, plate II, fig. 9 (description and illustration of the species; synonymy of S. ruficollis with X. carnifex ).

Trigoniulus carnifex -- Silvestri, 1896: 28 (species name mentioned).

Diaphoropus carnifex -- Silvestri, 1897: 651 (synonymised by Hoffman (1962)).

Xenobolus carnifex -- Carl, 1919: 394, figs 23–31 (description and illustrations of male). Attems, 1936: 304 (species name mentioned). Ganapati & Narasimhamurti, 1960: 581 (study on gut protozoa). Hoffman, 1962: 780 (species name mentioned; synonymy of E. phoenix with X. carnifex ). Mukherjee, 1962: 25 (segment variation study). Majumdar, 1967: 109 (study on gut protozoa). Rajulu, 1970: 143 (species name mentioned). Bano, 1983: 170 (species name mentioned). Achar, 1987: 149 (cytogenetic study). Alagesan & Vanithapriya, 1992: 299 (study on the biodigestion of millipede waste for biogas production). Valli, 1994: 322 (toxicity study). Jeekel, 2001: 54 (species name mentioned).Alagesan et al., 2003: 111 (study on gut bacteria). Alagesan & Muthukrishnan, 2003: 313 (study on the effect of temperature on embryology); 2005a: 5 (composition and biomass study); 2005b: 3 (bioenergetics study); 2009: 237 (study of population dynamics). Wesener et al., 2008: 38 (brief description of the species). Wesener & Enghoff, 2009: 110, figs 23D, 24B, 25A–C (illustrations and SEM images of male and female). Karthigeyan & Alagesan, 2011: 62 (millicompost study). Alagesan & Ramanathan, 2013: 1, Fig. 3 (brief description and image of the species); Bhakat, 2014: 185–186, 189–191 (water content analysis). Barber, 2015: 52, figs 1–3 (species name mentioned; images of the species). Chezhiyan & Prabakaran, 2016: 91, plate 2 (species name mentioned; image of the species). De Zoysa et al., 2016: 457 (species name mentioned). Golovatch & Wesener 2016: 34 (species name mentioned).

Erythroprosopon phoenix Verhoeff, 1936: 505 (description of the species), synonymised by Hoffman (1962).

Erythroprosopon phoenix -- Moritz & Fischer, 1975: 251 (species name mentioned).

Xenobolus acuticonus Attems, 1936: 303 , fig. 87a–d (description and illustrations of the species). New synonymy

Xenobolus acuticonus -- Natarajan, 1959: 92 (species name mentioned). Hoffman, 1962: 780 (suggested possible synonymy with X. carnifex ). Nagarbhushanam & Gokhale, 1968: 133 (species name mentioned). Rajulu, 1970: 143 (species name mentioned). Sharma & Handa, 1974: 678 (species name mentioned). Demange, 1977: 231 (species name mentioned). Chowdaiah & Kanaka, 1979: 17 (species name mentioned). Janardanan & Ramachandran, 1982: 239 (species name mentioned). Rangaswamy et al., 1983: 8 (species name mentioned). Bano, 1983: 170 (species name mentioned). Achar, 1987: 149 (cytogenetic study). Bai & Indra, 1997: 231 (brief description and natural history of the species). Jeekel, 2001: 54 (species name mentioned). Basil-Rose et al., 2014: 331 (study of hemagglutinability). Golovatch & Wesener 2016: 34 (species name mentioned).

Type materials. Type (? ♂ / ♀) of Iulus (recte: Julus ) carnifex from INDIA; D. Koenig leg.; date unknown; voucher number unknown; repository Zoological Museum, University of Copenhagen, not examined as the type material is lost (Enghoff, pers. comm.) [the original illustrations of X. carnifex given in Carl (1919) and the illustrations and SEM images of non-type material of X. carnifex presented by Wesener and Enghoff (2009) are diagnosable and were used for comparative purposes]. Type (♂) of Xenobolus acuticonus from INDIA: Madras; F.H. Gravely leg.; 22 August; voucher number unknown; repository possibly Indian Museum, Kolkata, not examined as the type is currently not in the myriapod collection kept in the National Zoological Collection, Kolkata (Sankaran, pers. obs.).

Topotype material ( X. acuticonus ) examined. INDIA, Tamil Nadu: Chennai, Tambaram, Madras Christian College campus (12 o 55’16.05’’N, 80 o 07’19.42’’E), 41 m alt., 9 December 2018, M.S Pradeep leg., from ground, by hand: 1 subadult ♀ (MILLI-ADSH0010). Chennai, Nungambakkam, Loyola College campus (13 o 03’48.14’’N, 80 o 14’04.36’’E), 15 m alt., 10 December 2018, M.S Pradeep leg., from ground, by hand: 1 ♀ (MILLI-ADSH0011). Chennai, Tambaram (12 o 55’29.75’’N, 80 o 06’00.01’’E), 19 m alt., 21 September 2019, M.S Pradeep leg., from ground, by hand: 6 ♀♀ (MILLI-ADSH0012) .

Other material ( X. carnifex ) examined. INDIA, Kerala: Palakkad, Thrippalur, Pullodu (10 o 38’16.58’’N, 76 o 33’52.87’’E), 70 m alt., 30 July 2017, M.S. Pradeep leg., from walls, by hand: 7 ♂♂, 5 ♀♀ (MILLI-ADSH0007). Ernakulam,Aluva, Thottakkattukara aqueduct (10 o 07’10.35’’N, 76 o 20’34.62’’E), 11 m alt., 23 July 2017, Jimmy Paul leg., from ground, by hand: 1 ♂, 1 ♀ (MILLI-ADSH0008). Ernakulam, Tripunithura, Hill Palace (9 o 57’09.32’’N, 76 o 21’50.13’’E), 29 m alt., 21 July 2018, Jithin Johnson leg., from bark, by hand: 1 ♀ (MILLI-ADSH0009) . Andhra Pradesh: Vijayawada , near railway station (16 o 30’54’’N, 80 o 37’22’’E), 30 m alt., 10 October 2019, M.S. Pradeep leg., from walls, by hand: 2 ♀♀ (MILLI-ADSH0013) .

Diagnosis. As in the generic diagnosis.

Redescription. Measurements: male with 50 body rings, circa 76 mm long, 5.4 mm wide. Female with 50 body rings, circa 76 mm long, 5.8 wide.

Colour. Aposematic colour pattern consisting blood-red (male)/orange (female) and black ( Fig. 1 A–B). Head, antennae, collum, ring 2, pre-anal ring, anal valves, legs blood-red/orange. Vertex between eyes black. Body rings except ring 2 laterally black, latero-basally and ventrally with a blood-red/orange stripe interrupted at posterior margin of metazonites with irregular creamy and black patches. Metazonites dorsally with a median blood-red/or- ange stripe consisting of an hour glass-shaped pattern ( Fig. 1 A–B). Colouration of preserved material: parts with blood-red/orange colour faded to yellowish red/yellowish orange. Metazonites greyish with irregular creamy-white markings.

Head. Head micropunctate, vertex prominent. Each eye patch with circa 48–50 ommatidia arranged in 7 or 8 vertical rows. Axial sulcus prominent, discontinued at frons. Labrum with four irregular teeth and a single row of 8 or 9 short marginal setae ( Fig. 2G ). Clypeus with four setiferous foveolae, two on each side. Antennal cavity present, slightly extending below eyes. Antennae short ( Fig. 2F ), protruding back to ring 2. Relative length of antennomeres: 1<2>3>4<5<6. Terminal antennomere with four large sensory cones located together inside a membranous area ( Fig. 4A ). Antennomere 5 apico-laterally with a field of 3 or 4 rows, antennomere 6 with 2 or 3 rows, of sensilla basiconica ( Fig. 4A , arrow).

Gnathochilarium. Usual for spirobolidans. Each lamella lingualis with two setae, located obliquely behind one another. Stipites with a slightly wavy lateral margin, each stipes with three stout apical setae ( Fig. 2G ) and an oblique transverse ridge directed towards mentum ( Fig. 2G ). Basal 2/3 mentum with several transverse ridges ( Fig. 2G ). Palpi with numerous sensilla ( Fig. 2G ). Hypopharyngeal crest with a field of spine-like structures ( Fig. 4B ). Central pads of endochilarium divided by a groove and a ridge into two separate regions ( Fig. 4B ; CP, Endo), distomesally with a group of circa 7 or 8 sensilla arranged in a circle ( Fig. 4B , inset), basally with more than 22 sensilla arranged in oblique vertical rows ( Fig. 4B ).

Mandible. Slim and elongated. External tooth simple, squarish ( Fig. 4C ; ET); inner tooth with three cusps ( Fig. 4C , 1 , 2 , 3; 3 IT), laterally an additional, isolated, simple tooth ( Fig. 4C ; LT). Pectinate lamellae arranged in 5 or 6 rows ( Fig. 4C ; PL). Mesal margin of pectinate area with a single row of small, slender spines continued with circa 4 or 5 rows of small spines baso-mesally ( Fig. 4C ); basal margin with 3 or 4 transverse rows of small spines ( Fig. 4C ). Molar plate long with>10 transverse furrows ( Fig. 4C ; MP).

Collum. Lateral margin rounded, not reaching the tips of ring 2, surface weakly punctate ( Fig. 2A, D ).

Body rings. Divided by sutures in three transverse zones, pro-, meso- and metazona. Meso- and metazonae dorsally micropunctate, ventrally with numerous weak longitudinal and oblique striations. Ozopore located on mesozona, starting with ring 6, located close to, but not touching suture between meso- and metazona. Pre-anal ring/epiproct sharp-edged, slightly extending beyond anal valves/paraprocts, more prominent in female ( Fig. 2C, E ). Anal valves with well-developed lips and micropunctuations, but with neither grooves nor setae ( Fig. 2C, E ). Subanal scale/hypoproct inconspicuous, widely triangular.

Legs. Coxae 1 and 2 elongated and fused with sternites. Coxae 1 unfused together, following ones remain adjacent ( Fig. 3A ). Leg-pair 2 longer than 1st ( Fig. 3B ); each podomere with apical/ventral/mesal stout and slender setae. Length of midbody legs circa 4.9 mm in males, circa 4.92 mm in females. Leg-pair 8 onwards in male and all legs in female, podomeres from coxa to tibia subdistally or distally with a single ventral spine. Tarsus with one stout dorso-apical and 3 or 4 ventral/ventro-mesal stout/slender spines in males, 4 or 5 ventral/ventro-mesal ones in females. Claw large, curved.

Male sexual characters. Coxae 3–7 modified, in particular 3rd and 4th with long, flat, rod-shaped, antero-mesal processes, 5th with a short, flat process, 6th and 7th with narrow, flat prominences ( Fig. 3 C–G). Podomeres from prefemur to tibia of leg-pairs 1–6 and prefemur to postfemur of 7th modified with flat ventral excrescences ( Fig. 3 A–G). Only body ring 7 conspicuously enlarged ( Fig. 2A ). Tips of gonopods visible in ventral view. Legs without tarsal pads.

Anterior gonopod. Sternite inverted V-shaped, with a median spatula-shaped process ( Figs 5A , 6A ; ST, msST). Coxite broad, with a thumb-shaped mesal process, flat in lateral view ( Figs 5A, B , 6 A–C; CO, mCO). Telopodite medio-laterally with paired globular processes ( Figs 5B , 6B ; gT1, gT2); retrorse process short, with a flat proximal half, distal half with a downwards directed, broad, conical process and a finger-shaped, laterally oriented, mesal process with apical bifurcations ( Figs 5A, B , 6A, B ; RT, cRT).

Posterior gonopod. Sternite narrow ( Fig. 6E ; ST). Main branch slender; tip broad, semi-circular in outline, fringed with numerous tiny conical processes, with a short, claw-shaped, mesal process, with a short branched process lying adjacent to the claw-shaped process, with a short conical process ( Fig. 6 D–F, arrows 1, 2, 3; MnB). Mesal branch broad, proximo-laterally with a broad, semi-circular, membranous lamella, ridged disto-laterally, mesally with a membranous, trapezoid process and a sharp hook ( Fig. 6D ; MsB, lmMsB, tMsB, hMsB).

Female copulatory organ (vulva). Simple, bivalve-like ( Fig. 7A, C ), consisting of two simple, subequally-sized, sclerotised valves ( Fig. 7 A–D; AV, PV). Each valve proximo-laterally bearing 2 or 3 rows of short setae located towards opening ( Fig. 7E ). ‘Operculum’ membranous, roughly circular with an anterior projection ( Fig. 7 A–D; O).

Variations. Males (n=8): 47–50 body rings; length 74–76 mm; width 5.1–5.4 mm; length of midbody legs 4.71–4.9 mm. Females (n=16, excluding the subadult one): 49–50 body rings; length 75–76 mm; width 5.6–5.8 mm; length of midbody legs 4.81–4.92.

Distribution. Currently known only from India (Andhra Pradesh, Kerala, Maharashtra, Tamil Nadu, West Bengal) and Sri Lanka (Colombo, Kandy, Maha Iluppalama) ( Fig. 9 ). Introduced populations are recorded in Australia ( Newport 1844a, 1844b) and Europe (Dublin, Ireland) ( Barber 2015). The record of X. carnifex in Borneo (Matang) ( Tömösváry 1885) is uncertain ( Pocock 1892). Records of X. carnifex in the U.S.A. ( Georgia) ( Koch 1847, 1863) are certainly wrong, even though Koch (1863) illustrated the species correctly ( Pocock 1892; Golovatch & Wesener 2016).

Natural history. Xenobolus carnifex is a synanthropic species and is mostly prevalent during the rainy season (June-July) ( Bhakat 2014; Sankaran, pers. obs.). It can be seen in open soils rich in organic matter, on fallen logs, on damp bricks and stones, as well as on wall surfaces and trunks of trees, all covered with bryophytes and fungi ( Bhakat 2014; Sankaran, pers. obs.). Rarely the species can be observed resting on the branches of shrubs (Sankaran, pers. obs.). During the rainy season, large numbers of individuals invade inside and on the roofs of buildings, thus becoming a nuisance pest ( Bai & Indra 1997; Alagesan & Muthukrishnan 2005b; Sankaran, pers. obs.).

Justification of the synonymy of X. acuticonus: Attems (1936) described X. acuticonus from Madras. It was characterised by a black body colouration, coupled with a row of hour-glass-shaped reddish spots on the dorsum, each male coxa 3 has a long process, an inverted V-shaped sternite of the anterior gonopods possesses a median spatula-shaped lamella, the anterior gonopod is with a broad coxite showing a short thumb-like mesal process, the telopodite medio-laterally has a globular process, the retrorse process of the telopodite features a downwards oriented flat and an antero-mesally oriented, finger-shaped process, the mesal branch of the posterior gonopod is with lateral ridges and a mesal hook and the main branch of the posterior gonopod has an apical fringe and a short, claw-shaped, lateral extension ( Attems 1936: fig. 87a–d). All these features are actually characteristic of X. carnifex (see Carl 1919: figs 25, 28–31; Wesener & Enghoff 2009: Fig. 25A–C). The topotype female genitalia of X. acuticonus match exactly in their structural details the female genitalia of X. carnifex (compare Fig. 7C with Wesener & Enghoff 2009: fig. 23D and herein Fig. 7A ). The generic distance analysis revealed that X. acuticonus differs from X. carnifex by a p-distance of 0.02% or mutations at 16 basepair positions ( Table 1). All these indicate, in agreement with Hoffman (1962), that in fact both X. carnifex and X. acuticonus belong to the same taxon. The species X. acuticonus is thus to be regarded as a junior synonym of X. carnifex .

Figures

FIGURE 1. Field photographs of Xenobolus carnifex (Fabricius, 1775). A: Male from Pullodu in Trippalur, Palakkad (MILLI- ADSH0007). B: Female from Pullodu in Trippalur, Palakkad (MILLI-ADSH0007). Photo courtesy Jimmy Paul.

FIGURE 2. Xenobolus carnifex (Fabricius, 1775) (MILLI-ADSH0007). A, D: Head and anterior trunk segments, lateral view. B: Legs 1–7, ventral view. C, E: Telson, lateral view. F: Left antenna, lateral view. G: Gnathochilarium, ventral view.A–C, F–G male, D–E female. Scale bars: A–B, D–E = 2 mm; C = 1 mm; F–G = 0.5 mm.

FIGURE 3. Xenobolus carnifex (Fabricius, 1775) (MILLI-ADSH0007), male legs 1–7. A: Leg-pair 1, ventral view. B: Leg-pair 2, ventral view. C: Leg-pair 3 (partly damaged), ventral view. D: Leg-pair 4, ventral view. E: Leg-pair 5, ventral view. F: Legpair 6, dorsal view. G: Leg-pair 7, oblique dorsal view. Scale bars: A–G = 1 mm.

FIGURE 4. Xenobolus carnifex (Fabricius, 1775) (MILLI-ADSH0007), male. A: Left antenna, antennomere 6 and disc, apical view (arrow indicates sensilla basiconica on antennomere 6). B: Central pads and palps, detail (inset sensilla on central pad). C: Left mandible, inner view (pectinate lamellae partly rubbed off). Abbreviations: 3IT = 3-combed inner tooth, CP = central pad, Endo = endochilarium, ET = external tooth, LT = lateral tooth, MP = molar plate, PL = pectinate lamellae. Digits 1, 2 and 3 indicate 3 combs of inner tooth. Scale bars: A–B = 0.1 mm; inset image 0.01 mm; C = 0.2 mm.

FIGURE 5. Xenobolus carnifex (Fabricius, 1775) (MILLI-ADSH0007), male. A: Anterior gonopods, ventral view. B: Same, dorsal view. C: Posterior gonopod, ventral view. D: Same, dorsal view. Scale bars: A–D = 1 mm.

FIGURE 6. Xenobolus carnifex (Fabricius, 1775) (MILLI-ADSH0007), male. A: Anterior gonopods, ventral view. B: Same, dorsal view. C: Same, mesal view. D: Telopodite of left posterior gonopod, ventral view. E: Left posterior gonopod, dorsal view. F: Enlarged view of distal part of left telopodite, dorsal view. Abbreviations: A = apodeme, cRT = conical process of retrorse process, CO = coxite, gT1 = first globular process of telopodite, gT2 = second globular process of telopodite, hMsB = hook-like process of mesal branch, lmMsB = lamellate process of mesal branch, mCO = mesal process of coxite, MnB = main branch, MsB = mesal branch, msST = median spatula-shaped process of sternite, RT = retrorse process, ST = sternite, tMsB = trapezoid process of mesal branch. Digit 1 claw-shaped mesal process, 2 branched process, 3 conical process. Scale bars: A–C, E = 1 mm; D, F = 0.5 mm.

FIGURE 7. Xenobolus carnifex (Fabricius, 1775) (MILLI-ADSH0007) (A–B, E) and Xenobolus acuticonus Attems, 1936 (MILLI-ADSH0011) (C–D), female. A, C: Vulva, lateral view. B, D: Same, dorsal view. E: Setae on valves, dorsal view. Abbreviations: AV = anterior valve, O = operculum, PV = posterior valve. Scale bars: A–D = 0.5 mm; E = 0.2 mm

FIGURE 8. Xenobolus carnifex (Fabricius, 1775) (A–C), original illustrations adopted from Carl (1919) and Xenobolus acuticonus Attems, 1936 (D), original illustrations adopted from Attems (1936).

FIGURE 9. Currently known distribution records of Xenobolus carnifex (Fabricius, 1775)../. records from literature:. type locality, new record (Maha Iluppalama is omitted from the map due to the unavailability of geographic coordinates).