IntroductionTop
The genus Euryurus Koch, 1847 was established to accommodate three species of Polydesmida of unknown geographic origin characterized by having a broad epiproct. Such a conspicuous feature seems to have been the source of a long history of taxonomic instability (Jorgensen, 2009, 2014). The three species originally described by Koch (1847) in Euryurus (E. maculatus Koch, 1847, E. margaritaceus Koch, 1847 and E. squamatus Koch, 1847) actually appear to be unrelated and belong to different families (Hoffman, 1978; Jorgensen, 2014). Since then, about 30 other species, mostly from the Neotropical realm, have been described as Euryurus, either as a full genus or as a subgenus (see a detailed bibliographic review in Jorgensen, 2014), including taxa later reassigned to the families Aphelidesmidae Brölemann, 1916 and Platyrhacidae Pocock, 1895.
During the 19th and 20th centuries, new genera and subgenera were established to accommodate several of these broad-epiproct species (e.g., Humbert & Saussure, 1869; Pocock, 1909; Carl, 1914), and currently the name Euryurus is restricted to 8 species distributed exclusively in the eastern United States (Jorgensen, 2009). Its suprageneric classification has also changed recurrently, being considered either as part of a tribe or a subfamily in the large, inclusive family Platyrhacidae (Pocock, 1909; Brölemann, 1916; Hoffman, 1975), or as a full-rank family, Euryuridae Pocock, 1909 (Hoffman, 1954, 1998), or more recently, as part of the family Xystodesmidae Cook, 1895 (Shelley & Smith, 2018; Means et al., 2021). Most species originally described in Euryurus are now reclassified in different genera.
According to Jorgensen (2014), of the multiple species once considered to be part of Euryurus, only two remain incertae sedis: Euryurus pallipes Koch, 1877 from Japan, and E. flavocarinatus Daday, 1889 from Mexico. Both species come from regions far from the known distribution of Euryurus and are most likely members of other genera.
Euryurus flavocarinatus was described from a single specimen collected in Mexico, without precise locality, by Janos Vadona (Daday, 1889). Unfortunately, ten years later Silvestri (1899) gave the exact same name to another species from Colombia, Euryurus flavocarinatus Silvestri, 1899. This case of primary homonymy was masked when Carl (1914) moved Euryurus flavocarinatus Silvestri into the newly created genus Pycnotropis Carl, 1914. However, probably as a consequence of this homonymy, it seems as if Daday's species had fallen into oblivion, and since its original description it has been incidentally mentioned only in just a few works (Attems, 1899; Korsós, 1983; Jorgensen, 2014). The holotype of Euryurus flavocarinatus Daday, a female specimen deposited in the Myriapod Collection at the Hungarian Natural History Museum, seems to have been revised at some point by R. L. Hoffman himself (E. A. Lazányi, pers. comm.), but to our knowledge he never published any observation of it, nor did he propose any new combination (e.g., Hoffman, 1978; 1999).
Here, we present a redescription of the holotype of Euryurus flavocarinatus Daday and propose a new combination by including it within the genus Amplinus Attems, 1898 of the family Aphelidesmidae. We also propose a new name for Euryurus flavocarinatus Silvestri, to resolve the primary homonymy of both names.
Material and methodsTop
The redescription of Euryurus flavocarinatus Daday, 1889 presented here is based on the examination of the holotype, the only known individual of the species. Examination and pictures of the holotype were made using a Leica MZ16A stereo microscope with a Leica DFC550 camera. Pictures were processed with software LAS v4.3. Measurements were taken with a Mitutoyo dial caliper with a resolution of 0.02 mm.
ResultsTop
After the examination of the holotype of Euryurus flavocarinatus Daday, 1889 it is clear that the species does not belong to Euryurus (Xystodesmidae). Instead, it is a species of Amplinus (Aphelidesmidae), as explained in the following taxonomic section. According to the article 57.2 of the International Code of Zoological Nomenclature, Euryurus flavocarinatus Daday, 1889 and Euryurus flavocarinatus Silvestri, 1899 are primary homonyms and the junior homonym is invalid; following article 60.1 the junior homonym must be replaced by an available and valid synonym or by a new substitute name. As there are no available synonyms for Euryurus flavocarinatus Silvestri, 1899, we propose a new name in the corresponding part of the taxonomic section:
Class Diplopoda de Blainville in Gervais, 1844
Order Polydesmida Pocock, 1887
Suborder Leptodesmidea Brölemann, 1916
Family Aphelidesmidae Brölemann, 1916
Genus Amplinus Attems, 1898
Amplinus Attems, 1898: 264. Type species: Polydesmus Klugii Brandt, 1839, by subsequent designation of Attems (1938).
Pseudamplinus Hoffman, 1954: 51. Type species: Amplinus orphnius Chamberlin, 1922, by original designation. Synonymized with Amplinus by Hoffman (1976).
DIAGNOSIS (after Hoffman, 1954 and Vohland, 1998)
Head with prominent subantennal swellings. Collum as wide as second tergite. Tergites strongly tessellated by polygonal areas forming transversal rows (Figs. 1B–D, 2A–B). Ventral surface of paraterga granulated. Epiproct broadly truncate distally, quadrate in appearance (Fig. 1D–E). Hypoproct trapeziform in shape; with two setigerous tubercles and with the margin between them straight or concave (Fig. 1E). Gonopods with very long, slender, coxosternal apodemes; coxae slender; prefemur and acropodite fused into a long, straight trunk, without sulcus between them; acropodite ending in a slender blade-like solenomerite and a thin flattened tibiotarsal process, both directed outwards, a third process present in a few species (see, for example, Hoffman, 1983: figs. 1–3, 5).
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Fig. 1.— Amplinus flavocarinatus (Daday, 1889) comb. nov. A) Cabeza; B) Collum y segmentos 3–4; C) Segmentos 11–12; D) Segmentos 17–19 y epiprocto; E) Epiprocto, paraproctos e hipoprocto; la flecha indica el fuerte tubérculo romo presente en los ángulos posteriores de los paraproctos; F) Esternitos de los segmentos 11–12. |
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Fig. 2.— Detalle de los metazonitos y paranotas de los segmentos 11–12 de A) Amplinus flavocarinatus (Daday, 1889) comb. nov., mostrando las áreas poligonales aplanadas y el patrón de disposición de lso tubérculos y B) Amplinus pococki (Cook, 1911) de Orizaba, Veracruz, México, mostrando las áreas poligonales abultadas típicas en la mayoría de las especies de Amplinus. |
REMARKS
The following species are currently recognized within Amplinus: Amplinus areatus Pocock, 1909; Amplinus armatus Pocock, 1909; Amplinus bitumidus (Loomis, 1969); Amplinus constrictus Chamberlin, 1953; Amplinus convexus (Carl, 1902); Amplinus erichsonii (Brandt, 1839); Amplinus flavicornis Pocock, 1909; Amplinus flavocarinatus (Daday, 1889) comb. nov.; Amplinus intermittens Causey, 1954; Amplinus klugii (Brandt, 1839); Amplinus leon Chamberlin, 1952; Amplinus manni Chamberlin, 1922; Amplinus mimus Chamberlin, 1953; Amplinus niteus Chamberlin, 1922; Amplinus nitidus (Brölemann, 1900); Amplinus orphnius Chamberlin, 1922; Amplinus palicaudatus (Attems, 1901); Amplinus permundus Hoffman, 1976; Amplinus pococki (Cook, 1911); Amplinus schmidti Chamberlin, 1952; Amplinus serratus Kraus, 1954; Amplinus tajumulco Chamberlin, 1952; Amplinus tapachulae Chamberlin, 1943; Amplinus triramus Pocock, 1909; Amplinus vergelanus Chamberlin, 1943; Amplinus xilitlus Chamberlin, 1943; Amplinus zunilus Chamberlin, 1952.
The genus ranges from northern Mexico (Nuevo León) to Costa Rica. Some South American species from Colombia and Venezuela have been placed in Amplinus (Hoffman, 1954; Jeekel, 1963): A. abstrusus (Karsch, 1881); A. ater (Peters, 1864); A. beebi (Chamberlin, 1950); A. cylindroides (Chamberlin, 1923). The generic status of these species needs to be revised (Hoffman, 1999).
Amplinus flavocarinatus (Daday, 1889) comb. nov.
urn:lsid:zoobank.org:act:106E9209-0821-4A43-B0EF-F0BFFB01B92A
Euryurus flavocarinatus Daday, 1889: 137 (original description). – Attems, 1898. – Korsós, 1983 (type information). – Jorgensen, 2014 (comment on its taxonomic status as incertae sedis).
EXAMINED MATERIAL
Female holotype, deposited at the Myriapod Collection of the Hungarian Natural History Museum (Budapest), from Mexico, without precise locality, with two labels: “Mexico, Lg. Vadona Janos” (white label, handwritten), “799/1887 Euryurus flavocarinatus Dad. Typ. Det. Dr. Daday Jenő” (white label, handwritten).
JUSTIFICATION FOR THE NEW COMBINATION AND COMMENTS ON POTENTIAL DIAGNOSTIC CHARACTERS
Amplinus flavocarinatus comb. nov. presents the typical habitus of Amplinus species, including tergites strongly tessellated by polygonal areas forming transversal rows (Figs. 1B–D, 2A), epiproct broadly truncate distally (Fig. 1D), hypoproct trapeziform in shape; with two setigerous tubercles and with the margin between them concave (Fig. 1E) and ventral surface of paraterga granulated (Fig. 1F). We lack information on the gonopod structure of this species, which is a large impediment for a clear diagnosis; examination of the only available specimen has shown a combination of characters that can help to identify Amplinus flavocarinatus comb. nov. from many species in the genus. Particularly, the flat, non-elevated polygonal areas in midbody metazonites (Fig. 2A), with medium-sized tubercles conspicuously aligned along frontal and posterior margins, and with small tubercles isolated in the center of some lateral polygonal areas, mostly on paranota (Fig. 1C), differ from those observed in most other Amplinus species, whose polygonal areas present a clearly swollen appearance (as, for instance, in Amplinus pococki Fig. 2B) (see the remarks section for a more detailed explanation). Other helpful characters areanterior corners of paranota from segments 2–11 slightly produced laterally, forming small, blunt teeth (Fig. 1B–C) and ventro-lateral angles of paraprocts (adjacent to the base of hypoproct) produced into a large blunt tubercle (Fig. 1E). However, for a full diagnosis of the species, examination of further material including adult males would be necessary, as well as a detailed reexamination of many Amplinus species currently incompletely characterized.
DESCRIPTION
Measurements: ca. 63 mm long, width, at collum = 7.1 mm, at 2nd segment = 7.56 mm, at 10th segment = 8.94 mm, at 19th segment = 5.50 mm. General habitus slender, W/L ratio ca. 14.2 %, dorsum convex, paranota set high on sides of metazonites, very slightly downturned. Color completely faded after more than 130 years in ethanol; according to the original description shiny, dark brown with yellowish paranota.
Head (Fig. 1A) glabrous, except for some large setae on anterior half of gnathochilarium (ca. 19 in right side), and setae on labrum (7 on right side). Prelabral setal insertions present (3+3), but setae missing. Vertex, frons, and clypeus (except frontal part) coriaceous. Labrum tridentate. Epicranial sulcus deep in frontal part of vertex and shallower in posterior part. Antennae robust and short, not extending up to posterior margin of frst segment when stretched backwards. Antennomeres covered with setae. Relative lengths of antennomeres 6>4=5=2=3>1>7.
Collum (Fig. 1B) glabrous, slightly elevated caudad, with anterior margin continuously arched and posterior margin almost straight; paranota tapering progressively, with blunt lateral ends. Surface with irregular, flat, non-elevated polygonal areas not forming transversal rows, larger in the middle. Medium sized tubercles concentrated on paranota and along posterior margin.
Body segments (Fig. 1B–C) with collum and second segment elevated caudad, following segments more leveled. Prozonites smooth. Surface of postcollum metaterga with three rows of well defined but flat, non-elevated polygonal areas in segments 2–5, larger in second row; in segments 6–17 the three rows more irregularly arranged and, in some areas, not clearly defined. In segments 18–19 polygonal areas less defined and mostly obscured by tubercles. Metaterga with medium sized tubercles aligned in single rows along frontal margin and, less conspicuously, posterior margin. Smaller tubercles present in center of lateral polygonal areas, strongly marked on paranota and progressively subdued towards the middle. Segments 18–19 (Fig. 1D) heavily tuberculate over their whole surface, with medium sized tubercles irregularly arranged in four to five irregular rows. Paranota (Fig. 1B–D) well-developed but narrow, with swollen lateral sides. Surface with polygonal areas and small tubercles. Anterior margin almost straight. Anterior corners of paranota from segments 2–11 slightly protruded laterally, forming small, blunt teeth; from segment 12 anterior corners rounded. Lateral margins slightly sinuous in outline, more clearly in porebearing segments. Posterior corner produced in a short tooth more obvious in central and posterior segments and not present in segment 2. Posterior margin slightly serrulated. Pores opening laterally following the regular distribution formula in segments 5, 7, 9, 10, 12, 13 and 15–19. Sternites (Fig. 1F) elevated, without longitudinal or transverse sulcus, and with small processes at base of each leg insertion, more conspicuous in posterior pairs, larger in anterior segments, progressively reduced and absent in segments 18–19. Lateral sides of metazonae granulated; with small tubercles in anterior and posterior margins and immediately below paranota. Legs with sparse setae, longer in coxa and prefemur, denser in tarsus. Claws short, about 1/3 the length of the tarsi.
Telson with epiproct (Fig. 1D–E) coriaceous with parallel lateral sides and roughly rounded posterior caudal margin with 5 shallow crenatures and fringed by nine long setae. Lateral borders of preanal ring with 2+2 setae. Hypoproct (Fig. 1E) wider than long with well differentiated paramedian setigerous processes. Paraprocts (Fig. 1E) with central swellings topped with single, long setae. Posterior angles of paraprocts adjacent to hypoproct protruded as a blunt large tubercule (white arrow in Fig. 1E).
REMARKS
Even if we have no information on the gonopod structure of Amplinus flavocarinatus, the female holotype presents a series of somatic features that could be useful as diagnostic characters, for instance the flat, non-elevated polygonal areas in three rows in midbody metazonites, with a well-developed row of tubercles along the anterior and posterior margins of metazonites and isolated small tubercles in the middle of some polygonal areas (Figs. 1C, 2A). In most species of Amplinus polygonal areas have a clearly swollen appearance, as tubercles are larger and more abundant, and in most polygonal areas they occupy the whole surface (Fig. 2B). In anterior and posterior most segments, metazonite tubercles are more similar to those found in other Amplinus species (Fig. 1B, D). In the case of A. flavocarinatus comb. nov., the flat polygonal areas make the anterior and posterior rows of metazonite tubercles more conspicuous than in other Amplinus species (Fig. 2).
Genus Pycnotropis Carl, 1914
Pycnotropis Carl, 1914: 419. Type species: Polydesmus (Euryurus) taenia Peters, 1864, by original designation.
Amydrinus Chamberlin, 1941: 500. Type species: Amydrinus pongus Chamberlin, 1941, by original designation and monotypy. Synonymized with Pycnotropis by Hoffman (1951, 1995).
Phinotropis Chamberlin, 1941: 499. Type species: Phinotropis tidus Chamberlin, 1941, by original designation and monotypy. Synonymized with Pycnotropis by Hoffman (1980, 1995).
Ptyxogon Chamberlin, 1941: 500. Type species: Ptyxogon incus Chamberlin, 1941. Synonymized with Pycnotropis by Golovatch et al. (1998).
DIAGNOSIS (after Hoffman, 1995, Golovatch et al., 1998 and Vohland, 1998)
Paranota thick. Caudal corners of paranota tapering in a more acute point only in paraterga 16 to 19. Polygonal areas weak, often restricted to lateral edges of paraterga or completely missing. Prefemur of gonopod about half total length of telopodite, set off distally by distinct constriction; two distal elements, one a short, falcate ventrally directed solenomerite with a distinct vesicle on ventral side of its base, the second (tibiotarsus) much longer, sinuate, flattened, ventrally directed (see, for example, Hoffman, 1995: figs. 1, 7, 11).
REMARKS
Pycnotropis has been revised and commented upon by Hoffman (1995), Golovatch et al. (1998) and Vohland (1998). The following species are currently recognized within Pycnotropis: Pycnotropis achiraensis Kraus, 1959; P. acuticollis (Attems, 1899); P. carli Golovatch, Vohland & Hoffman, 1998 P. curvata Golovatch, Vohland & Hoffman, 1998 P. falcata Golovatch, Vohland & Hoffman, 1998 P. goeldii Golovatch, Vohland & Hoffman, 1998 P. haenschi Carl, 1918; P. inca (Chamberlin, 1941) P. jeekeli Golovatch, Vohland & Hoffman, 1998; P. latzeli Attems, 1931; P. madeira Golovatch, Vohland & Hoffman, 1998; P. mammata (Attems, 1931); P. melanostigma (Silvestri, 1899); P. nitida Kraus, 1959; P. pallidicornis Golovatch, Vohland & Hoffman, 1998; P. sigma Golovatch, Vohland & Hoffman, 1998; P. silvestrii new name; P. similis Golovatch, Vohland & Hoffman, 1998; P. subareata (Jeekel, 1963); P. subfalcata Golovatch, Vohland & Hoffman, 1998; P. taenia (Peters, 1864); P. tida (Chamberlin, 1941); P. torresi Golovatch, Vohland & Hoffman, 1998; P. unapi Golovatch, Vohland & Hoffman, 1998; P. urucu Golovatch, Vohland & Hoffman, 1998; P. zumbii Golovatch, Vohland & Hoffman, 1998.
Most species in the genus Pycnotropis are endemic to Andean regions in Colombia, Ecuador and Peru, but some species are present in the Amazon Basin (Golovatch et al., 1998). One species, P. latzeli, was described based on a specimen apparently collected in Panama, although it could have been mislabeled (Golovatch et al., 1998).
Pycnotropis silvestrii new name
urn:lsid:zoobank.org:act:AF226F3A-6548-4451-A8BC-D596FABF0AE0
Euryurus flavocarinatus Silvestri, 1899: 68. Primary junior homonym of Euryurus flavocarinatus Daday, 1889.
Pycnotropis flavocarinatus (Silvestri, 1899): Carl, 1914: 936.
Pycnotropis flavocarinata (Silvestri, 1899): Golovatch et al., 1998: 68. – Vohland, 1998: 144.
DIAGNOSIS (FOLLOWING GOLOVATCH et al., 1998)
Colour uniform dark brown with lighter paraterga. Gonopod tibiotarsus rounded and slender, sigmoid (S-shaped); base of solenomerite with a triangular process (unmodified in P. madeira and P. urucu) (see Golovatch et al., 1997: fig. 82).
ETYMOLOGY
The species is named after Filippo Silvestri, who originally described the species, in honor of his great contribution to our knowledge of Diplopoda. The name is a noun in the genitive case.
RENARKS
The species is known only from the type locality: “Villavicencio m. 1000, Monteredondo-Buenavista, Dr. Bürger leg”. This is probably Villavicencio, Dept. Meta, about 65 km SE of Bogota.
DiscussionTop
The classification of many groups of millipedes is still far from resolved, from species to family level (Sierwald & Bond, 2007). This is true even in large, conspicuous organisms such as species within genus Amplinus, with about 30 currently recognized nominal species (27 from Mexico to Costa Rica, plus four more species of dubious generic identity from Colombia and Venezuela) (Jeekel, 1963; Hoffman, 1999). Any advance towards a comprehensive knowledge of the genus is hindered by the fact that many of these species are very poorly known and insufficiently described and diagnosed, and while some of the already named species may be junior synonyms of others, many additional species are yet to be described (Hoffman, 1983). Consequently, a full taxonomic revision of the genus Amplinus, with detailed examination and redescription of type specimens, would greatly help the study of its still largely unknown diversity (Hoffman, 1983; Vohland, 1998).
As in the case of Amplinus flavocarinatus comb. nov., several descriptions of Amplinus species are based on female type material, and the gonopod structure of these species have not been described. However, gonopod structure is highly homogeneous in most species of Amplinus, and somatic peripheral characters should be considered as additional source of diagnostic features, as has been observed in other large tropical polydesmidan millipedes (Hoffman et al., 2011; Recuero & Sánchez-Vialas, 2018). Even if some of these characters can present some degree of intraspecific variability, others seem to be more constant. For instance, color intensity and shade can vary among individuals in some Amplinus populations, but color pattern is mostly stable, as is the tubercle patterns and tessellation on the metazona. A combination of somatic characters could allow for specific identification even of females or immature specimens, at least for many described species. For this reason, detailed illustration of somatic peripheral characters is particularly important when describing or redescribing these species, a much needed task within the genus Amplinus (Hoffman, 1983). It is also very important to gather information on the intraspecific variability of these characters, since most species are known and described from very few specimens, sometimes only the holotype, and often from one to very few populations. In this context it is hard to tell if these characters have taxonomic value or if they may be too variable, as has been suggested in other members of the family (Golovatch et al., 1997, 1998; Vohland, 1998)
According to its metazonite sculpture, but also to other characters as coloration pattern and form of paranota and hypoproct, A. flavocarinatus comb. nov. could be closer to A. pococki and, particularly, to A. armatus Pocock, 1909. In fact, the detailed original description of A. armatus, based also on a single female specimen, fits almost perfectly with the holotype of A. flavocarinatus comb. nov. and, as suggested by Hoffman (1983) for some described species in the genus, both names could be synonyms. However, a thorough revision of Amplinus is needed to finally clarify the identity of these two species.
The holotype of A. flavocarinatus comb. nov. is a female from Mexico with no further information (Daday, 1889). The holotype of A. armatus, originally at the British Museum collections (Pocock, 1909), and currently lost according to Hoffman (1999), also came from Mexico with no other specific geographical information. Janos Vadona travelled in the early 1880s across central Mexico, from Veracruz to Guerrero, so defining the geographic origin with a minimum of accuracy of the holotype of A. flavocarinatus comb. nov. is not possible, and the geographical distribution of the species remains unknown until it can be found again in the field or in collections with properly labeled material. Two specimens at the Virginia Museum of Natural History collection, collected in Valle Nacional, Oaxaca, in central Mexico, were tentatively assigned to A. armatus by Hoffman (1999), but given the similarity among both species, they could also correspond to A. flavocarinatus comb. nov.
The existence of homonyms, particularly in species from the same genus or family, can result in one of the taxa falling into oblivion, as often only one of the names is consistently considered in catalogues, checklists or revisions while the exclusion of the other name is inherited in successive studies. The case of Amplinus flavocarinatus comb. nov. is not new among Mexican polydesmid millipedes, and it has been observed also at least in a case of secondary homonymy within the genus Myrmecodesmus Silvestri, 1910 (Shear, 1977; Hoffman, 1999; Recuero, 2014). Resolving homonymy cases is a first step in putting these species back into consideration for their study.