MYRIAPODOLOGICA

Virginia Museum of Natural History

Vol. 5, No. 12 ISSN 0163-5395 December 31, 1998

A new genus of spirostreptid millipeds from
Central America ( Spiro streptidae)

By Richard L. Hoffinaii

ABSTRACT

Three species of Centj'al American spirostreptids described by R, V.
Chamberlin (1922) in the genus Gynmostreptus (G. laetus, G. pacificus,
and G. vagam) are transferred into the new genus Mayastreptus (type
species G. vagans) on the basis on major differences from Brazilian
gyannostreptids in mouthpails, first male legs, and gonopods.

TAXONOMY

Several years ago, when investigating the status of some Brazilian spirostreptids
provisionally refered to Gymnostreptus, 1 became tangentially curious about the
identity of some supposedly congeneric species described by R, V. Chamberlin
(1922) from Costa Rica and Guatemala. In particular, the apparent absence of this
genus from most of northern Soutli America implied a major geographic lacuna in
the generic range that invited consideration. The examination of material
identifiable as Gymnostreptus vagam, one of the original Chamberlian species,
showed that despite a superficial similarity in gonopod structure (e g., a simple,
unbranched telopodite) with that of Brasilian species, most other characters
contraindicated any close relationship.

More receiiLly, compilation of a list of the Diplopoda of North and Middle
America compelled more serious inquiry' into this subject, the results of which are
set forth in the following pages. Isolation of the Central American taxa into a
separate genus appears to be the most reasonable disposition of the problem, with
the assumption that they represent local derivation from an initial occupation of that
region by species of Orthoporus.

Scanned with permission by Virginia Tech Insect Systematics Group 2014 (www.jointedlegs.org)

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Myriapodologica

Figs. 1-3. Mayas tre plus vagans, structural details. 1, mandibular psectromere, posterior
aspecp showing the two large teeth of the sectile sclente. 2, gnathochilarium, showing medial
absence of praebasilar plate and distal displacement of the stipital convexities. Stipital
marginal setae not shown. 3, coxae and leg bases of first legs of male, oral aspect. 4.
Gynmostrepius ventralis, basal elements of first male legs, oral aspect.

Hoffman: Spirostrcptidae
Mayastreptus, new genus

12 ]

Name: A neologism referring to one of the dominant Indian people of northeni
Central America.

Type species: Gymnostreptus vagans Chamberlin, 1922.

Diagnosis: Sectile sclerite of mandible (Fig. 1) with two large, elongated
subcqual "'teeth” and a small marginal lobe subtending the lower, the sectile edge
otherwise unmodified; mam body of psectromerc relatively short for a spirostreptid,
molar surface with a deep transverse apical groove. Pectinate lamellae closely
appressed and difficult to coimt. but apparently about 15. Prebasilar sclerite of
gnathochilarium (Fig. 2) represented in males only by the latcralmost ends, resulting
in a deep submental cavity for accomodation of the enlarged prefemoral lobes of the
1st pair of legs; latter elongate and cylindrical, medially in contact for much of their
length and projecting anteriad (Fig. 3); hypostome sclerite of normal appearance..

Gonopods (Fig. 5). Gonostemum small, transverse; paracoxites enlarged.
subglobose, attached to coxal region by flexible joint: anterior colpocoxal fold
simple, apically with a few scattered setae, posterior fold only slightly longer than
anterior, produced laterad as a small narrow projection. Telopodite in situ held on
anterior side of coxites, without prefemoral spine (“Kniedom”); area of torsion
elongated, broadened, extending proximad to level of paracoxites, torsion only 1 SO'"
or less, not localized as a tight 360° turn. Distal third of telopodite gradually
attenuated, mibranched, with a small subtenninal acute process (Fig. 6).

Bod> segments without notable modifications. Sensory' pit of 5th antennomere
unusLialU small. Coxal sockets of posterior legpairs closed behind by ends of
pleuroterga. Legs of males with postfemoral and tibial pads present back nearly to
posterior end of body.

Remarks: In the several species of Gymnostreptus known from Brazil and

Paragua\\ the prebasilar sclerite is not reduced medially and the prefemora of the
first male legs are only minimally produced into short low basal lobes (compare
Figs. 3 and 4). Actually the gnathochilarium and first male legs of M. vagans are
similar to the corresponding parts in Orthoporus, and it is not impossible that
Mayastreptus represents a local derivation from that genus by reduction of the apical
calyx of the gonotelopodite, a possibility- enhanced by geographic considerations
{Gymnostreptus in the strict sense bemg unknown north of the Amazon basin).

Species: Three, endemic in Guatemala, El Salvador, and Costa Rica.

Mayastreptus confragosus (Karsch), new combination

Spirostreptus (Nodopyyge) confragosus Karsch, 1881, Zeitschr. Naturw,, 54; 44.

$ holotype (ZMB) from “Costa Rica” without further data.

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Mynapodologi ca

Spirostrepti-is (Scaphiostreptus) confragosus: Brolemanii. 1905, Soc. ent. France, 74:
367, text fig. VII pi 9, fig. 20, pi 1 0, fig. 2 1 .

Orthoponis confragosus'. Pocock, 1909, Biol Centr.-Anier., Diplop., p. 101.
Gymnosireptus pad ficus Chamberlin, 1922, Proc. U. S, Nat. Mus., 60(8): 14, pi 7,
figs. 2-4. cf holofipe (USNM) from Santo Domingo de San Mateo, Prov. San
Jose, Costa Rica. New synonymy!

Episireptus (Microtrullius) paciftcus: Attenis, 1950, Ann. Naturh. Mus. Wien. 57:
218.

Although Brolemann was probably correct in identifying his material from San
Jose with the species described by Karsch, there will always be an element of
uncertainty until females can be compared directly with the t>pe specimen in Berlin.
For tliis reason 1 selected the nominal species vagans as type of Mayastrepius. There
seems to be no doubt, how^e\ er, that the name pacificus is strictiv conspecific with
what Brolemann called confragosus.

Mayastreptus laetus (Chamberlin), new combination

Gymnostreptus laetus Chamberlin, 1922, Proc. U. S. Nat. Mus., 60(8): 13, pi 6, figs.
7-9. 0 " holotype (USNM) from Joyabaj, Prov, Quiche, Guatemala.

Mayastreptus vagans (Chamberlin), new combination

Figs. 1-3, 5, 6

Gymnostreptus vagans Chamberlin, 1922, Proc U. S. Nat. Mus., 60(8): 13, pi 6,
fig. 10; pi 7, fig. 1. cf holotype (USNM) from ‘"Candelaria Rocks, Scamay
Estuaiy ”, Guatemala. According to Shear (1977: 341) “Scamay"’ is a mis-
spelling of “Seamay”, the name of three villages near Senahu, Dept. Alta
Verapaz.

Epistreptus (Microtrullius) vagans: Attems, 1950, Ann. Naturh. Mus. Wien, 57:
218.

Epistreptus (Microtrullius) vagans + pacificus: Kraus, 1954, Senckenb. biol. 35:
340, figs. 84-86.

Material Males and females (VMNH) from Fmca Cabanas at La Tinta, 140 m.
Dept. Alta Verapaz, Guatemala, G. Kramer leg. 24 April 1976.

Details of mouthparts and sexual characters are discussed above under the
generic heading and shown in the accompanying figures Routine peripheral body
structure is adequately accounted in the original description.

Hoffoian: Spirostreptidae

123

Figs, 5, 6. Mayastreptm vagans, gonopods. 5, right gonopods, anterior aspect. 6, distal end
of telopodite, enlarged.

Kraus (1954) ma)' have been correct to s}nonyniize pacificus with vagans,
although the gonopod illustration that he gave for Salvadorian material suggests
differences at some taxonomic level (as does the still extensive lacuna in the generic
range between Guatemala and Costa Rica). If the two names cited are eventually
proven to be synonyms, then both must be subsumed under confragosus.

124

Myri apodologica
LITERATURE CITED

Attems, C. 1950. Uber Spirostreptiden. Ann. Naturh. Mus. Wien, 57: 179-257, figs.
1-92.

Broleniann, H. W. 1905. M^riapodes de Costa Rica. Ann. Soc. Ent. France, 74;
337-380, figs. 1-28.

Chamberlin, R. V. 1922. The millipeds of Central America. Proc. U. S. Nat. Mus.,
60(8); 1-75, pis. 1-25.

Hoffrnan. R. L. 1997. Studies on spirostreptoid millipeds. XX. The taxonomic status
of three poorly-known species of Gynmostreptus from Brasil and Paraguay
(Spirostreptidac). Myriapodologica, 4; 59-83, figs. 1-17.

Karsch, F. 1881. Neue Juliden des Berliner Museums, als Prodromus einer Juliden-
Monographie. Zeitschr. Naturw., 54: 1-79.

Kraus, O., 1954. Myriapoden aus El Salvador. Senckenb. biol, 35: 293-349, figs.
1-97.

Shear, W3 A. 1977. Millipeds (Diplopoda) from caves in Mexico, Belize and
Guatemala. III. Acc. Naz. Lincei, Prob. Att. Sci. Cult. (Miss, ed Esplor.), 171(3):
235-265, figs. 1-56.

Address of the author:

Dr. Richard L. Hoffinan
Virginia Museum of Natural History
Martinsville, Virginia 24112, USA