Hoffman, Richard L.

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Papeis Avulsos de Zoologia MUSEU DE ZOOLOGIA DA UNIVERSIDADE DE SAO PAULO ISSN 0031-1049 Papeis Avulsos Zool., 37(11): 167- 172 10.IX.1990 CHELODESMID STUDIES. XXIII. PROPOSAL OF A NEW TRIBE FOR THE DISJUNCT BRASLLIAN GENUS MACROCOXODESMUS (DIPLOPODA: POLYDESMIDA: CHELODESMIDAE) Richard L. Hoffman1 Abstract The new tribe Macrocoxodesmini is proposed for the genus Macrocoxodesmus Schubart, 1947, with a single species known from Minas Gerais. Autapomorphies supporting this position include trichosteles on postfemora and tibiae of males, enormously enlarged valves of the cyphopods,and unusual curvature of the tracheal apodemes of the 2nd legpair in females. Fifty years ago, Count Attems (1938) recorded a total of six Brasilian genera of chelodesmids in his treatment of the family "Leptodesmidae", with the great majority of known species being aggregated into a large and heterogeneous genus Leptodesmus. Subsequently this number was increased to nearly 30, chiefly in numerous papers published by Otto Schubart, without any attempt being made to establish generic groupings at the tribal or subfamilial levels. Ongoing analysis of the Chelodesmidae commenced by me in 1969 has resulted in the definition of about a dozen tribes, occurring mostly in the southeastern states of Brasil and in the northern Andean region. The recent (May 1987) opportunity to examine the extensive chelodesmid mate- rial in the Museu de Zoologia, USP, disclosed that an already-known genus is sufficiently disjunct from its apparent nearest relatives to require accomodation in a monotypic tribal cate- gory which is here defined as many years may yet elapse before a summary of all Neotropical chelodesmids can be completed. For the most cordial hospitality and cooperation that has enhanced my study of MZUSP diplopods both "in situ" and on loan, I remain under continual obligation to Dr. P.E. Vanzonlini and Dr. J.L.M. Leme. Family Chelodesmidae Macrocoxodesmini, trib. n. Type genus: Macrocoxodesmus Schubart, 1947. Definition: Moderate-sized (length to 60 mm) chelodesmids with well-developed paranoia, body basically parallel-sided over segments 5 through 15, W/L ratio in the only included species, 12-13%. Metaterga microreticulate, with indistinct transverse sulcus; paranoia set high on sides, middorsum only slightly convex, paranoia slightly divergent posteriad, maximum width there- fore at their posterior comers which are acute on all segments and become increasingly pro- longed caudad on posterior segments; ozopores in normal sequence, located dorsally toward 1 Curator of Recent Invertebrates, Virginia Museum of Natural History, Martinsville, Virginia, 24112, USA. 168 Papeis Avulsos de Zoologia 5S -TV1--! 1 Figs. 1 -4, Macrocoxodesmus marcusi Schubart. 1. Leg from midbody segment, showing postfemoral and tibial trichosteles. 2. Seventh segment, ventral aspect, gonopods removed, showing size and shape of gonopod aperture. 3. Coxa of left gonopod, lateral aspect. 4. Left gonopod, mesal aspect, drawn from slide preparation with coxa slightly distorted. All drawings from male holotype. Vol. 37(11), 1990 169 ep 5 W m w W m w i V \ \\\ r w lV--, ta 6 ov 7 Figs. 5-7, Macrocoxodesmus marcusi Schubart. 5. Third segment in posterior aspect, showing modificatin of stemal region into "epigynal" flange. 6. Sternum and base of second pair of legs, anterior aspect, left cyphopod also shown. 7. Left cyphopod, posterior aspect. Drawings from female topotype. Abbreviations: ep, epigynal flange; ov, oviduct; s, stigmal opening; st, sternum, ta, tracheal apodeme. 170 Papeis Avulsos de Zoologia posterior end of prominent, flattened peritremata which at least on anterior half of body are distinctly set off from lateral edge; scapulorae of most segments with small acute dentation. Limbus unmodified. Epiproct distally acute. Sterna of midbody segments with two pairs of setiferous lobes which become smaller posteriad. Sternum of 4th segment with broad, spatulate median process covered, like coxae and prefemora of 3rd legs, with dense setation. Sterna of 5th and 6th segments each with an anterior pair of processes. Legs without trace of prefemoral knob and tibial pad, long and slender; 8th-16th pairs of legs of male sex with prominent trichosteles on ventral surface of postfemora and tibiae. Gonopod aperture extremely large, prolonged lateral beyond coxal sockets, extended also caudad between bases of 8th pair of legs nearly to caudal edge of segment, the rim not notably elevated or flared; posterolateral region of aperture with several distinct longitu- dinal ridges, median posterior area forming a shallow depression which accomodates bases of te- lopodites. Gonostemum large and prominent, distally truncate. Coxae large, subglobose, greatly prolonged distolaterad into acutely conical projection extending ventrad far beyond base of telopodite. Dorsal side of coxae with field of large setae adjacent to base of cannula. Te- lopodite relatively small, with large sinuously laminate prefemoral process; prostatic groove carried by a small, short solenomerite originating at distal end of prefemur, at the base of a large, distally broadened laminate element of uncertain anatomical identity, probably however postfemoral. Midventral region of 2nd segment of female elevated into prominent transverse lamina ("epigynum") behind base of 2nd legpair. Sternum of these legs slender, ventromedially pro- duced into a low intercoxal angle, stigmata prominently visible, open, more or less centered on coxal base; tracheal apodemes strongly curved mesad and nearly in contact, then recurved caudolaterally and divergent, without branch or projection near midlength. Coxae transversely elongate but not otherwise modified, nearly in contact medially. Receptacle of cyphopod undeveloped, operculum small; both valves enormously enlarged, flattened, densely setose, their distal margins each with three or four large dentations and smaller serrations; cyphopods in situ extending beyond rim of epigynal flange to a distance about equal to end of prefemora. Relationships: the form of the paranoia in M. marcusi strongly reminds of that developed in species of Odontopeltis (=Storthotropis of Attems and Schubart, see Hoffman 1984 for taxo- nomic and nomenclatorial clarifications), some of which are sympatric with marcusi. The totally different gonopod structure of Odontopeltis absolutely precludes any close relationship between the two genera, however, and the paranotal similarity can only be regarded as some form of convergence. On the other hand, both the gonopod aperture and gonocoxae suggest relationship with Eucampesmella and some related but as yet undescribed genera from northeastern Brasil. In the first category, the general size and shape of the aperture and the distinct posterolateral internal ridges are nearly identical in the several taxa. In the second, the pronounced lateral elongation of the coxa and the noteworthy field of large setae on the dorsal side also imply affinity. In Eucampesmella tricuspis (Attems), the prostatic groove is carried by a slender sub- acicular solenomerite which is as long as the other two major processes, and separated from the postfemoral element nearly down to their common base at the prefemur. A reduction in the length of this solenomerite would result in an effect like that presented by the gonopod of Macrocoxodesmus, and perhaps it is justified to consider this genus as a derivative of the Eucampesmella-gmup in which paranoia, male legs, and genitalia of both sexes have become extremely specialized. An investigation of Eucampesmella and some related taxa, now in progress, should result in the recognition of an additional and appropriate tribal group coordinate with the Macro- coxodesmini. For present purposes, it is sufficient to append some drawings and descriptive notes made from the type material of M. marcusi, to supplement the generally adequate original account of this species. Vol. 37(11), 1990 171 Macrocoxodesmus marcusi Schubart Figures 1-7 Macrocoxodesmus marcusi Schubart, 1947, Rev. brasil. Biol., v. 7, p. 110, figs. 1-4. Holotype male (MZUSP) from Fazenda Floresta, on the Rio Matipoo, Mun. Manhuassu and Ponte Nova, state of Minas Gerais. The original description of this species is long and detailed, and taken in connection with the illustrations provides a good concept of most important characters. Schubart gave figures of representative paranoia, legs structure, and gonopods in both dorsal and medial aspects. He did not speculate on the possible affinities of Macrocoxodesmus aside from placing it in a group of genera characterized by a combination of peripheral and genitalic characters ("...com distribui§ao normal dos poros, nao afastados da margem lateral, tergitos sem cerdas, prefemur das pemas do macho sem cones e com solenomerite nao circular"). It is not possible to state with certainty just which genera Schubart had in mind as components of this group. The original drawing (Schubart's fig. 4) of the gonopod in mesal aspect was made from a slide preparation in which the coxa is somewhat flattened by pressure of the cover slip, and in which the apices of the telopodite processes are tilted downward to a lower level (focal plane) than the basal region. The orientation of the drawing is thus decidedly an oblique ventromedian view. By fixing the entire preparation at a slight angle, I was able to obtain a much better mesal prespective. (fig. 4 of this paper) although deformity of the coxa could not be corrected. From my observation it could be established that the prefemoral process is set offbasally by a slight but still distinct cingulum. As seen in lateral aspect of the same gono- pod (fig. 3), the lateral coxal prolongation forms nearly a right-angle with the main axis of the podomere producing a configuration not known to me to occur elsewhere in the Chelodesmi- dae. The original description referred to (and illustrated) the occurrence of "cerdas grossas articuladas" on the ventral side of the tibiae. It was perhaps not entirely justified to use such a term, which implies that the hairs themselves are segmented. Actually, as the drawings clearly show, the hairs in question are placed at the tips of cylindrical trichosteles, where their mode of attachment does not seem especially different from setal sockets elsewhere on the integument. My study of the holotype showed these unusual structures to occur on legs of pairs 8 through 16, up to as many as 10 on the tibiae, but also usually one or two on the postfemora as well. Somewhat similar modifications occur on the legs of distantly related chelodesmids in the tribes Batodesmini and Trachelodesmini of the northern Andean region, but in these cases the hairs are associated with sphaerical or spiniform projections and occur at their base rather than apex. The female of marcusi was unknown to Schubart, but this sex is represented in material from the Rio Matipoo which he received at a much later date. Modifications of the 2nd pair of legs and cyphopods, as shown here in figs. 5-7, are so striking that they would not have escaped Schubart's notice had he female material at the time of describing marcusi. The enormous size of the valves and their striking dentation is not even approximated by any other chelodesmid so far known to me. To afford them some measure of protection epigynal region is accordingly more enlarged than in other genera. To date, this unusual species is known only from type locality. As this part of Brasil has scarcely been touched as regards sampling of the diplopod fauna, it is not unreasonable to assume that its actual range is much greater and more importantly, that additional species of Macrocoxodesmus will be found eventually. References Attems, C., 1938. Fam. Leptodesmidae, Platyrhachidae, Oxydesmidae, Gomphodesmidae. In Das Tierreich, lief. 69, pp. 1-487. 172 Papeis Avulsos de Zoologia Hoffman, R. L., 1981. Chelodesmid studies. XVII. Revalidation of the generic name Odontopeltis Pocock 1894, with the description of a new species and notes on other members of the group. Myriapodolo- gica, vol. 1, pp. 51-62. Schubart, O., 1947. Um novo representante da familia "Leptodesmidae", "Macrocoxodesmus marcusi" N G., N. SP. (Diplopoda). Rev. brasil. Biol., vol. 7, pp. 109-112. Publicado com o auxilio da Funda§ao de Amparo a Pesquisa (FAPESP. Processo n" 89/2401-1). 

Chelodesmid studies. XXIII. Proposal of a new tribe for the disjunct brasllian Genus Macrocoxodesmus (Diplopoda: Polydesmida: Chelodesmidae)

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Chelodesmid studies. XXIII. Proposal of a new tribe for the disjunct brasllian Genus Macrocoxodesmus (Diplopoda: Polydesmida: Chelodesmidae)

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