Chordodes balzani Camerano, 1896

De Villalobos, C., Hancock E. G. & Zanca F., 2004, Redescription and sexual dimorphism of Chordodes balzani Camerano, 1896 (Nematomorpha), Journal of Natural History 38, pp. 2305-2313 : 2306-2312

Chordodes balzani Camerano, 1896

( figures 1–11 )

Chordodes balzani Camerano, 1896: 10 .

NEOTYPE: Tamana Cave , Tamana Hill, Central Range Mountains , Trinidad ( Trinidad and Tobago), collected from host found on surface of bat guano, male, coll. E. G. Hancock, 8 July 1994 (deposited in the Hunterian Museum (Zoology), Glasgow, Acc. No. 110 821 ) .

Further specimens. A female with same data as neotype, collected on 4 July 1998 ( Hunterian Museum (Zoology), Glasgow, Acc. No. 110 822); Rio Cuchivero , Las Lomitas Caicara (6 ‡ 55’N, 68 ‡ 17’W), Venezuela, male, coll. O’Dent, 1905 (Musée National d’Histoire Naturelle, Paris, France, MNHNP Boccal: 288 No. 77) .

Remarks. The holotype as described by Camerano (1896) from Basso Beni ( Bolivia), a female collected by L. Balzan, cannot be located in the collection of the Museum Civico di Storia Naturale di Genova. Also, the male from Borba, Madeira River, Amazonas, Brazil, a male collected by Parko in 1943 (Museu Nacional, Rio de Janeiro, Brazil) seen by Carvalho (1946) and the female from San Pedro, Argentina, collected by Villa in 1946 (Museo del Instituto Miguel Lillo, Tucuman, Argentina, No. 66) and referred to by Carvalho and Feio (1950), cannot be found in the respective institutions. Unfortunately, they all seem to be lost. As a result of the detailed re-description of the species presented here we have erected a neotype in order to fix the name to this taxon. Thus, the only material available for SEM preparation of the cuticle are the specimens from Trinidad and Venezuela.

Host. Final instar nymph of Eublaberus posticus (Erichson) (Dictyoptera, Blaberidae ) collected from surface of bat guano from which the Chordodes emerged subsequent to collection.

Description of male from Trinidad

Length 324 mm; diameter 2.1 mm. Anterior end tapered, mouth terminal. Ventral side marked by a darkly pigmented line. Posterior end rounded ( figure 1 ). Cloacal opening subterminal, oval (61.1 M m long627.7 M m wide) with circumcloacal spines, and situated ventrally at 190 M m distant from the posterior margin of the body. Anterolateral of the cloacal opening are paired regions in which numerous bristles are located (bristlefields). These bristles are maximally 18 M m long, the majority unbranched, but a few are branched apically ( figure 2 ). Anterior and posterior region of the cloacal opening covered with short spines ( figure 1 ). The body colour is uniformly black-brown.

The cuticle shows variation along the length of the body. In the anterior region, close to the mouth, there is only a single type of areole, rounded, 3.5–5.6 M m diameter and 4.9–5.3 M m high ( figure 3 ). The apical surface of these areoles is smooth or bears fine tubercles. The inter-areolar space is narrow, 1.4 M m, from which occasional apically rounded tubercles protrude, some of them up to 9.1 M m high and others slightly shorter.

In the medium region of the body ( figures 4 , 5 ) the cuticle contains six different types of areole which are numbered consecutively for the purpose of description and orientation. The most abundant are oval or rounded areoles ( type 1, figures 4 , 5 ), the same as those at the anterior end. Similarly, between these type 1 areoles there are scattered apically rounded tubercles (13.3 M m high). Among type 1 areoles occur type 2 areoles, which are higher than type 1 (15.5 M m), pyramidal and with small hyaline projections at the top ( figure 4 ). Seen directly from above these can be seen to be arranged in pairs ( figure 5 ). The third areolar type ( figures 4–6 ) is more elevated than the first two (18.9–19.9 M m), being conical and with a ring of short, sharp bristles at the apex. These occur in clusters of from 19 to 23 areoles that surround areoles of type 4 ( figure 6 ). Areoles of type 4 always occur in pairs and are not as high as type 3 (15.9–16.2 M m), with moderately short filaments at the apex. These are the so-called crowned areoles. In the longitudinal ventral groove in the cuticle (arrowed in figure 7 ) there are two further types of areole ( figure 8 ). The type 5 areole in the ventral groove forms clusters numbering from 12 to 15 areoles, and are rounded (9 M m in diameter) with an irregular, granular surface. Their surface is covered by numerous blunt bristles (length: 5.2 M m). Type 6 areoles are abundant, short, with ill-defined borders, and in some cases they appear to be more like cuticular creases than areoles. Amongst these type 5 and 6 areoles a quantity of elongated tubercles (9.2 M m) with a moderately sharp apex are located.

Description of female from Trinidad

Length 380 mm; diameter 2.1 mm. The anterior end is tapered and the mouth aperture ( figure 9 ) is terminal, lined by papular structures. The cuticle immediately surrounding the mouth has irregular folded ridges in a radial pattern. The cloacal opening is situated terminally at the posterior end. The body colour is uniformly blackish brown as in the male. Ventral, dorsal and lateral grooves are clearly visible. The cuticle shows, as in the male, surface variations in the different regions of the body. At the anterior end the cuticle has a crinkly appearance ( figure 9 ). In the mid-body region there are six types of areoles. Types 1 and 2 are the same as in the male. Female type 3 areoles are distributed as in the male but they exhibit a scaly surface with no bristles at the apex ( figure 11 ). Areole types 4 and 5 are also different from the male. Female type 4 crown areoles, with short filaments, are distributed along almost all of the body and are similar to the crown areoles of the male. Female type 5 crown areoles have long filaments, about 280 M m in length ( figure 10 ) which are also paired and occur in rows along the ventral and dorsal midline. Both these kinds of crowned areoles in the females are surrounded by type 3 areoles forming areolar groups. The cuticle is densely covered by type 6 areoles ( figures 10, 11 ) which have a rugose appearance; among them rounded-apex tubercles can be found occasionally.

The male specimen from Venezuela

Length, 335 mm; diameter, 1.6 mm. Body colour is brown. The posterior end and the cuticle show the same features as the male from Trinidad. This specimen was determined by Dorier in 1905 as Chordodes sp. (on a manuscript label) but was not cited in any of his publications.

Discussion

In the original description of C. balzani , based on a female, Camerano (1896) described the cuticle as having three areolar types, corresponding with our types 1, 3 and 4, detailed above. He later described and illustrated ( Camerano, 1897: figure 20, 20a, 20b) darker pairs of areoles, some of them surrounding a tubercle, located among (our) type 1 areoles without considering them structurally different from any of the others. These pairs of areoles correspond with our type 2 areoles. Carvalho and Feio (1950) described a male and a female as having four areolar types. Camerano (1897) and Carvalho and Feio (1950) described, in females, crown areoles with long filaments (our type 5) located in the dorsal groove as well as in the dorsal and ventral one. They did not distinguish the other crown areoles with short filaments distributed over the cuticle (our type 4) as described here in the Trinidad female. Similarly, detail of these cuticular features of C. balzani were not mentioned by Camerano (1896, 1897) or Carvalho and Feio (1950). Analysis by SEM shows with more precision the cuticular variation between different regions of the body and between the areoles themselves which enables us to increase the number of recognizable areolar types to six. The male and the female specimens of C. balzani differ in some respects from each other. Although types 1, 2 and 4 areoles are similar in both sexes and type 3 shows a slight difference, types 5 and 6 areoles are quite different.

The presence of crown areoles with long filaments limited to the lateral groove in females has been mentioned for other South American species, C. brasiliensis Janda (see Janda, 1894; Camerano, 1897; Carvalho, 1946), C. carmelitanus ( Carvalho and Feio, 1950) , C. staviarskii Carvalho and Feio, 1950 and C. peraccae (see De Villalobos and Zanca, 2001). This particular feature in females was considered to be a sexual dimorphism by Carvalho (1946) for the species C. brasiliensis and by Camerano (1897) and Carvalho and Feio (1950) for C. balzani . Nevertheless, Schmidt-Rhaesa (2002) observes crowned areoles with long filaments, along the ventral and dorsal midline, and crown areoles with short filaments over the cuticle in both male and female specimens of C. queenslandi Schmidt-Rhaesa, 2002 from Australia. Although more studies are necessary on both sexes of other species of this genus in the Neotropical Region, sexual dimorphism appears to be a consistent feature of the species examined so far from the neotropics with modern methods.

At the posterior end of the male, the occurrence of the paired bristlefields anterolateral of the cloacal opening has been recorded in C. matensis ( De Villalobos and Miralles, 1997) , C. cornuta ( De Villalobos and Camino, 1999) , C. festae ( De Villalobos and Zanca, 2001) from South America, and C. queenslandi and C. brevipilus Schmidt-Rhaesa, 2002 from Australia. This feature occurs in a number of other nematomorphan genera such as Beatogordius (Schmidt-Rhaesa et al., 2002) , Euchordodes , Gordionus , Parachordodes and Paragordionus (Schmidt-Rhaesa, 1997) .

The cockroach host species ( Eublaberus posticus ) of the C. balzani specimens from Trinidad has not been recorded previously, as specimens have usually been found in their free-living state. It is important to note that in spite of the usual relationship between the gordiids of the genus Chordodes and praying mantids (Schmidt-Rhaesa and Ehrmann, 2001), there are records of four species of Chordodes known to be parasites of cockroaches (see Schmidt-Rhaesa, 2001; Schmidt-Rhaesa and Ehrmann, 2001). Of these three are South American C. matensis in Blaptica sp. ( De Villalobos and Miralles, 1997), C. moraisi (Carvalho, 1943) in Blatta orientalis Linnaeus, 1758 ( Carvalho, 1944) and C. peraccae in Ischnoptera brasiliensis Wattenwyl, 1865 ( Camerano, 1915; De Villalobos and Zanca, 2001) to which C. balzani can now be added. There are not enough data to indicate to what extent this may be facultative or might indicate a restriction in host range.

Chordodes balzani has been reported previously from Bolivia ( Camerano, 1896, 1897) and Argentina and Brazil ( Carvalho and Feio, 1950). From this study Venezuela and Trinidad and Tobago extend the known distribution of the species.

Figures

FIGs. 1–4. SEMs of Chordodes balzani, male specimen from Trinidad. (1) Ventral view of the posterior end. Note the cloacal opening (co) with circum-cloacal bristles and bristlefields anterolateral of the cloacal opening (black arrow). (2) Higher magnification of the bristlefields (black arrow). (3) Cuticle of the anterior end. (4) Mid-body cuticle with areolar types 1, 2 and cluster containing types 3 and 4. Bars: 100 Mm (1, 4); 10 Mm (2, 3).

FIGs. 5–8. SEMs of Chordodes balzani male from Trinidad. (5) General dorsal view of mid-body cuticle with areolar types 1, 2 and clusters containing types 3 and 4. Note that type 2 areoles are always arranged in pairs. (6) Areolar clusters with types 3 and 4. (7) Longitudinal ventral groove, clusters of areoles of type 5 (black arrow) are distributed along each side of the ventral midline. (8) Areolar types 5 and 6 in the longitudinal ventral groove. Scattered tubercles occur between areole types 5 and 6 and minute bristles can be seen on the surface of areole type 6. Bars: 100 Mm (5, 7); 10 Mm (6, 8).

FIGs. 9–11. SEMs of Chordodes balzani female from Trinidad. (9) Anterior end with mouth opening surrounded by papular structures (black arrow). (10) Longitudinal ventral groove with clusters of areoles of types 3 and 5 (black arrow) distributed along each side of the ventral midline, areole type 5 with long filaments. (11) Areolar cluster of types 3 and 5 surrounded by type 6. Bars: 10 Mm (9); 100 Mm (10, 11).