Miscel.lania Zoologica 20.1 (1997) 119

The antennal basiconic sensilla and of Machilinus Silvestri, 1904 (Insecta, , Microcoryphia)

M. J. Notario-Muñoz, C. Bach de Roca, R. Molero-Baltanás & M. Gaju-Ricart

Notario-Muñoz, M. J., Bach de Roca, C., Molero-Baltanás, R. & Gaju-Ricart, M., 1997. The antennal basiconic sensilla and taxonomy of Machilinus Silvestri, 1904 (Insecta, Apterygota, Microcoryphia). Misc. ZOO~.,20.1: 119-123.

The antennal basiconic sensilla and taxonomy of Machilinus Silvestri, 1904 (Insecta, Apterygota, Microcoryphia).- Some special antennal sensilla ('rosettenformige' and basiconica) of five species of Mach~fihus(Mei nertellidae): M. casasecai, M. helicopalpus, M. kleinenbergi, M. rupestris gallicus and M. spinifrontis were studied. The distribution patterns of the sensilla are different for each examined species and identical in both sexes. The sensillogram thus provides a good taxonomic characteristic for their identification.

Key words: Taxonomy, Antennal sensilla, Basiconic sensilla, Machilinus.

(Rebut: 8 VI1 96; Acceptació condicional: 4 XI 96; Acc. definitiva: 17 XII 96)

María José Notario-Muñoz, Rafael Molero-Baltanás & Miguel Gaju-Ricart, Depto. de Biología (Zoología), Univ. Córdoba, 14005 Córdoba, España (Spain).- Carmen Bach de Roca, Depto. de Biología Animal, Vegetal y Ecología, Univ. Autónoma de Barcelona, Bellaterra 08193, Barcelona, España (Spain). l This work was supported by Fauna Ibérica III SEUI-DGICYT PB92-0121.

O 1997 Museu de Zoologia Notario-Muñoz et al. lntroduction M. casasecai Bach, 1974, 8 88 y 2 99, Lérida (Spain) 28 V 86; M. spinifrontis Bach, The ' antennae are provided with 1984, 4 88' y 5 99, Jaén (Spain) 11 VI1 82 specialized sensilla which function, rnainly, and 10 X 82. as chaernoreceptors. Their nurnber and dis- The specimens were preserved with 70% tribution along the antennal flagellurn have alcohol. Their antennae were dissected and been suggested as characteristics with taxo- mounted with Tendeiro medium, the slides nomic (LARINK,~~~~)and phylogenetic were dried and clarified in a heater at 35OC (WALTHER,1983) irnportance. for 30 days. The sensillograrns of sorne Machiloidea The slides were observed with conven- ( and ) were car- tional optic microscopy or, when neces- ried out by BOCKHORST(1988) who studied sary, with differential interference contrast the distribution of al1 sensilla Dresent in the (Nomarsky). antenna (chaetica, trichodea, basiconica, Like al1 insects, Microcoryphia antenna coeloconica and 'rosettenformige') with are cornposed of scape, pedicel and fla- optical and electron rnicroscopy. Using Scan- gellum, the latter with a variable number ning Electron Microscopy (SEM), BACHet al. of annuli which, on the distal part, are (1986) and FANCIULLI et al. (1988) provided arranged in clear groups called 'distal more data about the types of Microcoryphia chains', also variable in nurnber and sepa- antennal sensilla. rated by a narrow part. The distal chains The scales cover a great part of the of al1 Machilinus are composed of eight Microcoryphia body. In rnost Machilidae, annuli except M. rupestris gallicus which these scales are present al1 around the has nine. antenna, but this is not so in the case of The distal chains are enumerated from Meinertellidae. The study of sensilla is the apex to the scape (n, n-1, n-2, n-3, therefore easier. etc.). To identify each annuli of a given As fernales of Machilinus lack the sec- distal chain, they are enurnerated in the ondary sexual characters present in males, same way, the distal being number one and these cannot be identified at a specific the basal number eight or nine (fig 1). The leve1 in rnany cases. different kinds of sensilla are named with The aim of the present study was to letters (A, B, C, etc.) preceded by the number evaluate whether the distribution pattern of sensilla per annuli (IBZCID: one sensillum of the basiconic antennal sensilla in B and D and two sensilla C). Machilinus can be used as a specific charac- ter and whether it remains immutable in males and fernales of a given species. Results

The sensilla studied are the basiconic and Material and methods 'rosettenformige'. Al1 different types are represented in figure 2. The nurnber and The study was carried out with five position of each one of them are indicated Machilinus species. To give taxonomic sig- in table 1. nificance and avoid differences related to The 'rosettenformige' sensillum is widely geographical distante, the studied rnate- represented in many Microcoryphia species rial was collected near description locality and can be found in different parts of the of each species. body. In al1 stcidied species, only one sensillum per annuli has been found and is Studied material therefore not included in table 1. M. kleinenbergi (Giardina, 1900), 3 88 y 19, Another sensillurn present in al1 studied Siena (Italy) 25 Vlll 89 and 23 IX 95; M. species is the B (fig. ZB), which like the helicopalpus Janetschek, 1954,8 88 y 5 99, remaining sensilla is basiconic. Only one Ávila (Spain) 10, 11 VI 95; M. rupestrisgallicus sensillum has been found in the first annuli Bitsch, 1968,3$8 y 3 99 (paratypes) France: of each distal chain. It is srnall, sunken and Draguignan 29VI 64and Roquebrun 6 VI1 58; cornpletely hidden, with only a srnall Miscel.lania Zoologica 20.1 (1997) 121

; rp::;:18 n 1 8 n-1 E P F -

Fig. 1. Outline of Machilinus antenna: E. Scapus; F. Flagellum; n. Last distal chain; n-l. Penultimate distal chain; P. Pedicel; 1. Distal chain annuli 1; 8. Basal chain annuli 8. (Scale 0.05 mm.) Esquema de antena de Machilinus: E. Escapo; F: Flagelo; n. Última cadena distal; n-l. Penúltima cadena distal; P. Pedicelo; 1. Anillo 1 (distal); 8. Anillo 8 (basal). (Escala 0,OS mm.)

-A ~3l'/~{/- +&$=pp

A B @I 4 bE& flGl?j

Fig. 2. Special sensilla in Machilinus antennae: A. "rosetenformige" sensilla; B-H. Basiconic sensilla. (Scale 0.01 mm.) Sensilios especiales en las antenas de Machilinus: A. Sensilio en roseta; 8-H. Sensilios basicónicos. (Escala 0,01 mm.)

cuticular opening to the outside. most frequent case; sometimes this number The C sensillum is the typical basiconic changes in different distal chains of the one (fig. 2C); It is found in al1 the species, same antenna. Moreover, as demonstrated but its number and position changes. The by BACHet al. (1986) and FANCIULLI et al. annuli 3 always presents the highest num- (1988) using SEM, different types may be ber (between two and four). The numbers found beneath its shape. expressed in table 1 correspond to the The D sensillum (fig. 2D) is very close in 122 Notario-Muñoz et al.

Table 1. Patterns of distribution of the sensilla in the studied species represented by means of the last two distal chains (n and n-1). All annuli present a special sensilla (A), not indicated because of its constancy. Annuli 6 to 8-9 have been omitted since they lack special basiconic sensilla: Mc. M. casasecai; Mh. M. helicopalpus; Mk. M. kleinenbergi; Mr. M. rupestris gallicus; Ms. M. spinifrontis. Patrones de distribución de los sensilios de las especies estudiadas, representadas mediante las dos últimas cadenas distales (n y n-1). Todos los anillos presentan sensilio A que no se ha incluido debido a su constancia. Se han omitido los anillos del 6 al 8-9 porque carecen de sensilios basicónicos especiales: Mc. M. casasecai; Mh. M. helicopalpus; Mk. M. kleinenbergi; Mr. M. rupestris gallicus; Ms. M. spinifrontis.

Annuli n n-1 n n-1 n n-1 n n-1 n n-1

3 1G2C 1G2C 1F3C 1F3C 3C 4C 4C 4C 1F2C IF2C - 4 5 IDIC IEIC IEIC ID IDIC 1H 1H 1E IEIC

shape to C but is stronger. It has been llogram for each species. found only in two species M. kleinenbergi Sometimes the sensilla can appear thin- and M. casasecai. It is placed in a small ner than usual. This can be due to altera- cuticle depression. tions after the manipulation of the an- The sensillum E (fig. 2E) is present in M. tenna. However, they can be precisely helicopalpus and M. spinifrontis. It is simi- distinguished by their constant position and lar in shape to D but shorter and quite the characteristic cuticular base of each broad, inserted into a relatively wide and type. deep cuticular depression. The sensillum tip Curiously, the pattern implies not one, is always clearly seen outside. These two but two distal chains; so is a replication species present another sensillum (F) very (n+n-1 = n-2+n-3 = n-4+n-5= etc). Every two close to E, but narrower (fig. 2F). distal chains represent the sensillogram for M. casasecai has a unique sensillum (G) each species. not found in the remaining species (fig. 2G). The distribution partterns from table 1 The sensillum shape is like C but is inserted include only the last two distal chains. in a deep narrow cuticular depression; its tip is practically at surface level. Finally M. rupestris gallicus has another Discussion typical sensillum (H) not found in the other species (fig 2H). The sensillum shape is simi- In general the sensillograms expressed in lar to E of M. helicopalpus, but closest to G table 1 are coincident with the results given of M. casasecai by its position in a deep by BOCKHORST(1988) though the author cuticular depression; its tip never protrudes presents a lineal arrangement of al1 sensilla outside. found, from the first to the last flagellum All these sensilla are located in a con- annuli. The differences with our results are crete position. As a result, the overall set related to the sencillum C which is consid- provides the distribution pattern or sensi- ered by the author as containing various Miscel.lania Zooloaica 20.1 (1997)

subtypes. BACHet. al. (1986) and FANCIULLIet aparece en la misma posición y número para al. (1988) found various types of sensilla C todas las especies (sensilio B); los restantes using SEM. Their cuticular surfaces may be tipos de sensilio, o bien son exclusivos de rough or smooth. This type of sensillum, algunas especies o bien varían en posición y although differing in number and position número. among the species, does not appear to be En la tabla 1 se da el patrón de distribu- essential for the pattern, at least in the ción (sensiliograma) de todas las especies studied species, sensilla D, E, F, G and H estudiadas. Únicamente se indican los being much more important. Only M. sensilios presentes en las dos últimas cade- helicopalpus presents as characteristic a C nas distales, ya que, sa ha comprobado, sensillum on annuli 2. Once the sensillogram que es el conjunto de dos cadenas lo que of al1 Machilinus species is known, it might constituye el sesiliograma, repitiéndose el be of interest to determine the differences mismo a lo largo del flagelo. between subtypes of sensillum C. La importancia del hallazgo de esta BOCKHORST(1988) found differences be- característca radica en que el mismo sensi- tween sensilla of M. spinifrontis in males liograma se encuentra tanto en machos, and females. This was not so with our speci- como en hembras, como en individuos ju- mens, as we found the distribution pattern veniles (subadultos) permitiendo la identifi- for each species to be perfectly coincident cación específica de los ejemplares que ca- in both sexes. Those differences are due recen de caracteres sexuales secundarios without doubt to individual alterations of (hembras y juveniles). some specimen and to the low quantity of material studied. In conclusion, not only the kind of sen- silla are characteristic for some species, but Ref erences also their distribution Dattern, which shows constancy for males, females'and subadult BACH,C., DALLAI,R., FANCIULLI,P. P. & GAJU,M., specimens. It would therefore seern that 1986. Characteristics of some species of this taxonomic character should be included Catamachilis (Insecta, Apterygota) ob- with the description of any new species. served under Scanning Electron Micro- scope. Redia, 69: 489-522. BOCKHORST, K. G., 1988. Sensillenmuster auf Resumen den Antennen verschiedener Machiliden (Insecta: ). Braunschw. Los sensilios basicónicos de la antena y taxo- naturkdl. Schr. 3(1): 137-170. nomía de Machilinus Silvestri, 1904 (lnsecta, FANCIULLI,P. P., BACH,C., DALLAI,R. & GAJU,M., Apterygota, Microcoryphia) 1988. Morfología de la hembra de tenuicornis Stach 1930, al mi- Se han estudiado los sensilios especiales de croscopio electrónico de barrido (Apte- tipo roseta "rosettenformige" y basicónicos rygota: Microcoryphia). Eos, 64: 63-71. que se hallan en las cadenas distales de las LARINK,O., 1986. Pattern of Antennal Sensilla antenas de cinco especies de Machilinus: M. in some Lepismatidae (Insecta: Zygen- casasecai, M. helicopalpus, M. kleinenbergi, toma). 2nd Int. Seminar on Apterygota: M. rupestris gallicus y M. spinifrontis. En 237-242. todas las especies las cadenas distales cons- WALTHER,JR., 1983. Antennal Patterns of tan de ocho anillos excepto las de M. Sensilla of the Hymenoptera. A complex rupestris gallicus que poseen nueve. Se han Character of Phylogenetic Reconstruction. hallado siete tipos diferentes de sensilios Verh. naturwiss. Ver. Harnburg (NF), 26: basicóncos (fig. 2) de los cuales sólo uno 373-392.