Ityphilus betschi, Abstract, 2010

Pereira, Luis Alberto, 2010, First Record Of A Ballophilid Centipede From French Guiana With A Description Of Ityphilus Betschi Sp. Nov. (Myriapoda: Chilopoda: Geophilomorpha), Papéis Avulsos de Zoologia 50 (42), pp. 643-665 : 644-659

Ityphilus betschi sp. nov.

( Figs. 1-52 )

Diagnosis: An Ityphilus species with internal edge of forcipular tarsungulum partially serrate; ventral porefield series present along the entire body length; all pore-fields undivided. For a confident identification, the new species is compared in detail to the other Neotropical members of the genus sharing these three combined traits, and having a roughly similar range of leg-bearing segments, i.e., I. crabilli Pereira, Minelli & Barbieri, 1994 (from Brazil); I. demoraisi Pereira, Minelli & Barbieri, 1995 (from Brazil); I. guianensis Chamberlin, 1921 (from Brazil, Guyana, Trinidad); I. perrieri (Brölemann, 1909) (from Brazil); and I. saucius Pereira, Foddai & Minelli, 2000 (from Brazil). I. betschi sp. nov. can be distinguished from these latter taxa by the following unique traits (the corresponding ones in the other five species are given in parentheses): body length up to 57 mm (15 to 32 mm); a.a. III and IV slightly longer than wide, a.a. XIII as long as wide (antennal articles I to XIII, all wider than long); ratio of length of a.a. XIV/length of antennal articles XI to XIII taken together, ca. 0.62: 1 (from ca. 0.85: 1 to ca. 1.05: 1); forcipular coxosternite: ratio of maximum width/length at the middle, ca. 2.70: 1 (ca. 1.73: 1 to ca. 2.42: 1).

The relatively high ratio of length/width of the apical a.a. (= ca. 2.6: 1); relative large size of the calyx of poison gland ( Figs. 23 , 30 ); high ratio of length of telopodite of the ultimate legs/length of sternite of the male ultimate leg-bearing segment (= ca. 3.2: 1); and the presence of diminutive hair-like structures on the posterior edge of the labral mid-piece ( Fig. 16 ), are also distinctive features for this species.

Morphological traits in Table 1 differentiate I. betschi sp. nov. from I. crabilli ; I. demoraisi ; I. guianensis ; I. perrieri ; and I. saucius .

Type material examined: Holotype male ( MNHN Collection Myriapodes et Onychophores: M354), 67 leg-bearing segments, body length 40 mm, from French Guiana: piste de St. Elie : 16 km from Sinnamary, ca. 73 m a.s.l., (Lat ( DMS) 04°49’60”N, Long ( DMS) 53°16’60”W), 26 March 1977, J.-M. Betsch leg.

Other material examined: female ( MNHN Collection Myriapodes et Onychophores: M354), 71 leg-bearing segments, body length 57 mm, from French Guiana: Petit Saut : Fleuve Sinnamary, ca. 19 m a.s.l., (Lat ( DMS) 05°20’60”N, Long ( DMS) 53°40’60”W), 13 October 1989, H.P. Auberlenc, leg.

Remarks: The adult condition of these specimens is confirmed by the presence of mature spermatozoa in the tubula seminifera of the male, and spermatozoa in the spermathecae of the female. (This is easily observable at the compound microscope from the specimens mounted on temporary slides).

Male holotype: Sixty-seven leg-bearing segments, body length 40 mm. Trunk attenuate on anterior and posterior regions, with exception of the ultimate leg-bearing segment which is conspicuously wider than the penultimate, in the ratio 1.47: 1 ( Figs. 41-42 ). Width of selected leg-bearing segments as follows: 1 (0.71 mm); 3 (0.62 mm); 4 (0.68 mm); 10 (0.80 mm); 21 (1.0 mm); 35 (1.15 mm); 57 (0.90 mm); 62 (0.80 mm); 66 (0.68 mm); 67 (1.0 mm). Width of cephalic plate, ca. 0.72 mm. Width of forcipular coxosternite, ca. 0.77 mm. Ground color (of preserved specimen in alcohol) pale ocher.

Antennae: nearly contiguous, ca. 3.0 times as long as the cephalic plate, somewhat curved at the middle ( Figs. 2 , 8 ), distally slightly thickened ( Figs. 1-2 , 8 ). Antennal article XIV apically blunt, nearly as long as the sum of the two previous articles. Apical club extends over a.a. VIII to XIV of which a.a. VIII is transitional, being narrow at the base and slightly widened distally ( Figs. 1-2 , 8 ). Ratio of width of a.a. IX (= widest antennomere of distal antennal half)/width of a.a. IV (= narrowest antennomere of basal antennal half), ca. 1.25: 1. Length/width ratio of right antennal articles I-XIV (in ventro-dorsal position), as follows: I (0.61: 1); II (0.83: 1); III (1.02: 1); IV (1.11: 1); V (0.94: 1); VI (0.88: 1); VII (0.84: 1); VIII (0.81: 1); IX (0.85: 1); X (0.88: 1); XI (0.93: 1); XII (0.93: 1); XIII (1.0: 1); XIV (2.6: 1). A.a. VIII to XIV slightly flattened dorso-ventrally. Ventral chaetotaxy: setae on a.a. I to VII of various lengths and relatively few in number, those of a.a. VIII to XIV much shorter and very numerous ( Figs. 1-2 ). Dorsal chaetotaxy: setae on a.a. I to VII similar to those on ventral side, setae on a.a. VIII to XIV much less numerous and a little longer than those on ventral side. A.a. XIV with ca. 31 claviform sensilla on the external border and ca. 27 on the internal border ( Fig. 3 ); distal end of this a.a. with ca. 13 very small hyaline specialized sensilla apparently not split apically ( Fig. 3 ). Ventral and dorsal surface of a.a. II, V, IX and XIII with very small specialized sensilla. On the ventral side, these sensilla are restricted to a middle latero-internal area on a.a. II and V ( Figs. 4-5 ) and to an apical latero-internal area on a.a. IX and XIII ( Figs. 6-7 ), and are represented by two different types: a and b. Type a sensilla are very thin and not split apically ( Fig. 7 : a); type b sensilla ( Fig. 7 : b) are very similar to those on the apex of a.a. XIV. Specialized sensilla on dorsal side distributed on the apical half of the specified antennal articles ( Figs. 9-12 ), and are represented by three different types: a and b, similar to a and b of ventral side ( Fig. 12 : a, b); and type c sensilla “spine-like”, larger, not divided apically, and slightly darker (pale brownish-ochreous) in color ( Fig. 12 : c). Number and distribution of specialized sensilla on a.a. II, V, IX and XIII, as in Table 2 .

Cephalic plate: ca. as long as wide, shape and chaetotaxy as in Fig. 13 . Ratio of maximum width of cephalic plate/maximum with of forcipular tergite ca. 0. 98: 1.

Clypeus: with 2+2 setae near the anterior margin and 1+1 setae in the middle ( Fig. 14 ).

Labrum: poorly pigmented; mid-piece membranous, slightly and irregularly undulated, with posterior edge provided with diminutive hair-like structures only visible at high magnification ( Fig. 16 ); side-pieces with 5+4 small and sharply pointed denticles ( Fig. 15 ).

Mandibles: dentate lamella with all teeth of similar size, not subdivided into blocks, 9 teeth in the right mandible ( Fig. 17 ), 10 teeth in the left mandible; pectinate lamella with ca. 39-44 hyaline teeth.

First maxillae: with lappets on the coxosternite and telopodites ( Figs. 18-19 ). Coxosternite without setae; coxal projections subtriangular, well-developed and provided with 1+1 setae ( Figs. 18, 20 ). Telopodites apparently without visible suture between the presumptive basal and distal articles, ventral surface bearing 1+1 setae on the middle part of medial edge ( Fig. 18 ), dorsal surface with 2+2 sub apical sensilla ( Fig. 19 ).

Second maxillae: coxosternite without any trace of suture along the sagittal plane and provided with 6+6 setae arranged as in Fig. 18 . Apical claw of telopodites well-developed, bipectinate, dorsal edge with ca. 26 teeth ( Fig. 21 ), ventral edge with ca. 19 teeth.

Forcipular segment: when closed, the telopodites do not extend beyond the anterior margin of the head. Forcipular tergite wider than the tergite of the first leg-bearing segment, chaetotaxy represented by ca. 40 large setae dispersed on almost the whole surface ( Fig. 29 ). Coxosternite: with incomplete chitin-lines ( Fig. 22 : a); maximum width/length ratio at the middle ca. 2.70: 1; central part of the anterior margin with shape as in Figs. 22 , 29 . Telopodites: all articles without teeth; trochanteropraefemur with greatest length/greatest width ratio ca. 1.17: 1; tarsungulum with a very small, unsclerotized and pale, round-tipped chitinous thickening on the basal part of the medial edge ( Figs. 22 , 29 ); internal edge of tarsungula serrate on the proximal half, left tarsungulum with 11 teeth ( Fig. 23 ), right tarsungulum with 10 teeth ( Fig. 30 ). Calyx of poison gland cylindrical ( Figs. 23 , 30 ). Shape and chaetotaxy of coxosternite and telopodites as in Figs. 22 , 29 .

Legs (pair 1 to penultimate): first pair ca. as long as the second pair, articles of leg-pair 1 a little narrower than those of leg-pair 2 (relative size as in Figs. 22, 24 ); chaetotaxy of legs similar throughout the entire body length. Distribution, number, and relative size of setae as in Figs. 24-26 . Claws with two thin and pale accessory spines ventrobasally, one anterior very small and one posterior much larger (shape and relative size as in Figs. 27-28 ).

Sternites of leg-bearing segments 1 to penultimate: pore-fields present in an uninterrupted series, from sternite 2 to penultimate inclusive. All pore-fields undivided and placed on a subcircular-subovoidal raised prominence. Form and relative size of fields changing along the trunk as in Figs. 31-40 . Number of pores on selected sternites as follows: sternite 2 (8); 3 (27); 7I (125); 12 (204); 27 (298); 41 (259); 54 (195); 61 (146); 65 (64); 66 (29).

Ultimate leg-bearing segment: conspicuously wider than the penultimate leg-bearing segment, in the proportion 1:46: 1; intercalary pleurites present at both sides of the ultimate pretergite; ultimate presternite divided along the sagittal plane; length/width ratio of the tergite, 0.77: 1; length/width ratio of the sternite, 1.13: 1. Shape and chaetotaxy of tergite and sternite as in Figs. 41-42 . Coxopleura with numerous setae distributed on the whole ventral and lateral surfaces, dorsal side with setae placed near the lateral edges only ( Figs. 41-42 ). Two single (“homogeneous”) coxal organs of similar size in each coxopleuron, coxal pores opening on the membrane between coxopleuron and sternite, partially covered by the latter ( Fig. 42), internal cuticular structure as shown in Figs. 44, 46 (a: mucous layer). Right coxal organs accompanied by a very small supernumerary organ ( Fig. 44 : a, Fig. 45 ), opening independently by a little pore on the coxopleural surface ( Fig. 45 : c). Ultimate legs with seven articles. Articles strongly thickened, femur wider than all the other telopodite articles (ratio of width of femur/width of tarsus 2 ca. 2.33: 1). Ultimate legs remarkably long. Ratio of length of telopodites of ultimate legs/length of sternite ca. 3.20: 1. Ratio of length of telopodites of ultimate legs/length of legs of penultimate pair ca. 1.56: 1. Shape and chaetotaxy of ultimate legs as in Figs. 41-42 . Ultimate pretarsus represented by a long, straight, setiform structure accompanied by a very small spine ( Fig. 43 ).

Postpedal segments: intermediate tergite with posterior margin strongly convex ( Fig. 41 ), intermediate sternite and first genital sternite with posterior margin slightly convex ( Fig. 42). Gonopods apparently uniarticulate (suture between the presumptive basal and apical articles not evident), left gonopod with 10 setae on ventral side ( Fig. 47 ). Penis apparently devoid of setae, shape as in Fig. 48 .

Female (specimen cited above): seventy-one leg-bearing segments, body length 57 mm, maximum body width 2.0 mm. All features similar to those in the male except for the shape and chaetotaxy of the ultimate leg-bearing segment and postpedal segments.

Ultimate leg-bearing segment: wider than the penultimate leg-bearing segment in the ratio 1.33: 1; length/ width ratio of tergite, 0.73: 1; length/width ratio of sternite 1.13: 1. Shape and chaetotaxy of tergite and sternite as in Figs. 49 , 51. Coxopleura very slightly protruding at their distal-internal ventral ends, setae numerous on the whole ventral and lateral surfaces, dorsal side with few setae placed near the lateral edges only ( Figs. 49 , 51). Articles of ultimate legs, strongly thickened, subconically narrowing from base to distal end (ratio of width of trochanter/width of tarsus 2 ca. 2.69: 1); ultimate legs relatively shorter than those of the male, with ratio length of telopodites/length of sternite, 1.96: 1. Shape and chaetotaxy of ultimate legs as in Figs. 49 , 51.

Postpedal segments: intermediate tergite with posterior margin strongly convex ( Figs. 49-50 ); intermediate sternite with posterior margin slightly convex, posterior margin of first genital sternite, nearly straight ( Figs. 51-52). Gonopods uniarticulate not contiguous in the middle line, each bearing a single seta ( Figs. 51-52).

Remarks: In the preceding description, length/width ratios of the antennal articles have been taken from the right antenna because it remained in an adequate ventral-dorsal position on the temporary slide ( Figs. 1 , 8 ). In contrast, the apical half of the left antenna remained in a latero-ventral position ( Figs. 2 , 8 ). Because the a.a. VIII to XIV are slightly flattened dorso-ventrally, it was not appropriate to take those comparative indices from this latter antenna.

For details on fine structure and function of coxal organs, see Rosenberg & Seifert (1977); Lewis (1981); and Rosenberg (1982, 1983).

Etymology: The species is dedicated to the collector of the holotype, Dr. Jean-Marie Betsch of the Muséum National d’Histoire Naturelle (Department Ecologie et Gestion de la Biodiversité, Brunoy, France).

Ecology: The two specimens described above were collected in tropical rainforest environments in equatorial Amazonia.

Type locality: French Guiana: piste de St. Elie: 16 km from Sinnamary.

Known range: French Guiana: piste de St. Elie: 16 km from Sinnamary; Petit Saut: Sinnamary River.

Complementary notes on some Neotropical species of Ityphilus morphologically similar to I. betschi sp. nov. (with which the latter is herein compared in detail)

Figures

FIGURE 41: Ityphilus betschi sp. nov., (male holotype): Penultimate and ultimate leg-bearing segments, and postpedal segments, dorsal. Scale bar: 1.0 mm.

FIGURES 1‑5: Ityphilus betschi sp. nov., (male holotype; French Guiana: piste de St. Elie: 16 km from Sinnamary): (1) Right antenna, ventral; (2) Left antenna, latero-ventral (external) view; (3) Rigth a.a. XIV, ventral (a: claviform sensilla, b: apical specialized sensilla); (4) Right a.a. II, ventral (b: b type sensilla); (5) Right a.a. V, ventral (a, b: a, b type sensilla). Scale bars: 0.3 mm (1-2); 0.1 mm (3-5).

FIGURES 6‑10: Ityphilus betschi sp. nov., (male holotype): (6) Right a.a. IX, ventral (a, b: a, b type sensilla); (7) Right a.a. XIII, ventral (a, b: a, b type sensilla); (8) Contour of antennae, ventral; (9) Right a.a. II, dorsal (a: a type sensilla); (10) Right a.a. V, dorsal (a, b: a, b type sensilla). Scale bars: 0.3 mm (8); 0.1 mm (6, 7, 9, 10).

FIGURES 11‑14: Ityphilus betschi sp. nov., (male holotype): (11) Right a.a. IX, dorsal (a, b, c: a, b, c type sensilla); (12) Right a.a. XIII, dorsal (a, b, c: a, b, c type sensilla); (13) Cephalic plate and basis of antennae; (14) Clypeus. Scale bars: 0.1 mm (11-12); 0.4 mm (13); 0.3 mm (14).

FIGURES 15‑16: Ityphilus betschi sp. nov., (male holotype): (15) Labrum; (16) Detail of mid-piece of labrum at high magnification (showing diminutive hair-like structures). Scale bars: 0.2 mm (15); 0.05 mm (16).

FIGURES 17‑21: Ityphilus betschi sp. nov., (male holotype): (17) Dentate lamella of right mandible; (18) First and second maxillae, ventral; (19) Left side of first maxillae, dorsal; (20) Detail of first maxillary coxal projections, ventral; (21) Claw of left telopodite of second maxillae, dorsal. Scale bars: 0.05 mm (17, 21); 0.3 mm (18); 0.2 mm (19); 0.1 mm (20).

FIGURES 22‑28: Ityphilus betschi sp. nov., (male holotype): (22) Forcipular segment and leg-bearing segment 1, ventral (a: chitin-line); (23) Detail of duct and calyx of poison gland in left forcipular telopodite, ventral; (24) Right leg (pair 2), ventral; (25) Right leg (pair 34), ventral; (26) Right leg (pair 54), ventral; (27) Claw of left leg (pair 5), postero-lateral view; (28) Claw of the right leg (pair 34), anteroventral view. Scale bars: 0.5 mm (22); 0.1 mm (23); 0.3 mm (24-26); 0.05 mm (27, 28).

FIGURES 29‑34: Ityphilus betschi sp. nov., (male holotype): (29) Forcipular segment and leg-bearing segment 1, dorsal; (30) Detail of duct and calyx of poison gland in right forcipular telopodite, ventral; (31-34) Sternites of leg-bearing segments 2, 3, 7 and 12 respectively. Scale bars: 0.5 mm (29); 0.1 mm (30); 0.3 mm (31-34).

FIGURES 35‑40: Ityphilus betschi sp. nov., (male holotype): Sternites of leg-bearing segments 27, 41, 54, 61, 65 and 66 respectively. Scale bar: 0.3 mm.

FIGURES 43‑48: Ityphilus betschi sp. nov., (male holotype): (43) Detail of distal end of right ultimate leg, ventral; (44) Right coxal organs, ventral (a: small supernumerary coxal organ); (45) Detail of supernumerary coxal organ marked as “a” in Fig. 44 (a: mucous layer, b: channel, c: coxal pore); (46) Left coxal organs, ventral (a: mucous layer); (47) Left gonopod, ventral; (48) Penis, dorsal. Scale bars: 0.05 mm (43, 45, 47); 0.2 mm (44, 46); 0.1 mm (48).

FIGURES 49‑50: Ityphilus betschi sp.nov., (female;French Guiana: Petit Saut: Fleuve Sinnamary): (49) Penultimate and ultimate legbearing segments, and postpedal segments, dorsal; (50) Detail of intermediate tergite. Scale bars: 1.0 mm (49); 0.3 mm (50).