Pachymerium mundus, (Chamberlin, 1955)
publication ID |
https://doi.org/ 10.11646/zootaxa.4027.4.3 |
publication LSID |
lsid:zoobank.org:pub:4218E1CD-9016-47C3-A1DA-291F9C53661F |
DOI |
https://doi.org/10.5281/zenodo.5667412 |
persistent identifier |
https://treatment.plazi.org/id/875F87C1-FFAA-3C26-FF11-EEB436B1FD7F |
treatment provided by |
Plazi |
scientific name |
Pachymerium mundus |
status |
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Plateurytion mundus ( Chamberlin, 1955)
( Figs. 1–53 View FIGURES 1 – 4 View FIGURES 5 – 10 View FIGURES 11 – 19 View FIGURES 20 – 25 View FIGURES 26 – 36 View FIGURES 37 – 39 View FIGURES 40 – 44 View FIGURES 45 – 53 )
Chilerium mundum Chamberlin, 1955: 23 , 24.
Eurytion mundum: Crabill, 1968:231 View in CoL ; Foddai, Pereira & Minelli, 2000:75, 182. Eurytion mundus: Pereira, 2006:167 (in key).
Plateurytion mundus : Bonato, Pereira & Minelli, 2007:6; Pereira, 2008:56.
Diagnosis. A species of Plateurytion characterized by having one cluster of coxal organs in each coxopleuron of the ultimate leg-bearing segment. Of the other South American species currently included in the genus, only the present species and P. zapallar ( Chamberlin, 1955) share the same character. Plateurytion mundus can be confidently differentiated from P. zapallar by means of the following selected traits (the corresponding ones in the latter are given in parentheses): body length of female 35–45 mm (28 mm, female; 27 mm, male); female with 49, 51 leg-bearing segments (female with 47, 49, probably 51, 53; male with 47, 49, 51); dorsal side of a.a. XIII with ca. 14 type b and ca. 6 type c specialized sensilla, Fig. 4 View FIGURES 1 – 4 (with ca. 3 type b and ca. 1 type c, Fig. 59 View FIGURES 59 – 66 ); teeth of labrum midpiece short, slightly sharp-pointed, Fig. 8 View FIGURES 5 – 10 (similar to the long filaments of the side-pieces, but thinner and smaller, Figs. 63, 64 View FIGURES 59 – 66 ); second article of telopodite of first maxillae with ca. 12–13 setae (with ca. 4–7); ventral pore-fields undivided on metasternite 1, divided in two areas on metasternites 2 to penultimate, Figs. 15–29 View FIGURES 11 – 19 View FIGURES 20 – 25 View FIGURES 26 – 36 , 45–51 View FIGURES 45 – 53 (undivided on metasternites 1 to ca. 15, divided in two areas on remaining metasternites including penultimate, Figs. 73–85 View FIGURES 67 – 74 View FIGURES 75 – 80 View FIGURES 81 – 88 ); with ca. 20–25 organs in each cluster of coxal organs in the coxopleura of the ultimate leg-bearing segment, Fig. 39 View FIGURES 37 – 39 (with ca. 8–11 organs in each cluster, Figs. 96 View FIGURES 95 – 98 , 104 View FIGURES 99 – 104 ).
Other morphological traits included in Table 1 View TABLE 1 differentiate P. mundus from P. zapallar .
Remarks. P. mundus can be separated from the other South American members of Plateurytion using the identification key below.
Type material examined. CHILE: 35 km E of Temuco, winter of 1951, M. G. Smith col., three syntypes here designated as lectotype ♀ with 49 l. -b.s., b.l. 45 mm (head capsule, dissected mouth parts, leg-bearing segments 44–49, and postpedal segments in an original permanent slide; forcipular segment, and leg-bearing segments 1–43 in alcohol); paralectotype A ♀ with 51 l. -b.s., b.l. 35 mm (in alcohol); paralectotype B ♀ with 51 l. -b.s., b.l. 37 mm (in alcohol). All specimens labeled as Chilerium mundum Chamberlin ( CAS Entomology type No. 9173).
Remarks. Chamberlin (1955) stated that the syntypical series comprised four specimens, but actually comprises three (apparently one of these is now missing). Left forcipular telopodite, pretarsus of left ultimate leg, and last three apical articles of right ultimate leg, missing in lectotype ♀.
Depository of types. CAS.
Redescription. Female lectotype. Forty nine leg-bearing segments, body length 45 mm, maximum body width 1.9 mm. Maximum width of cephalic plate 1.08 mm, length of cephalic plate 1.74 mm, maximum width of forcipular coxosternite 1.70 mm. Color (of preserved specimen): head and forcipular segment light chestnut, rest of the body yellowish light orange.
Antennae. About 2.95 times as long as the cephalic plate, distally attenuate ( Fig. 1 View FIGURES 1 – 4 ). Ratio of width of a.a. II/ width of a.a. XIV ca. 2.08: 1, all a.a. longer than wide. Ventral chaetotaxy: setae on a.a. I–VI (VII) of various lengths and relatively few in number; those of remaining a.a. progressively shorter and more numerous towards the tip of the appendage ( Fig. 1 View FIGURES 1 – 4 ). Dorsal chaetotaxy: setae on a.a. I–VI (VII) similar to the ventral side, setae on remaining a.a. a little longer and slightly less numerous. A.a. XIV with ca. 29 claviform sensilla on the external margin and ca. 16 on the internal margin ( Fig. 2 View FIGURES 1 – 4 : a); distal end of this a.a. with ca. 5–6 very small hyaline specialized sensilla, having about half the length of the claviform sensilla and not split apically ( Fig. 2 View FIGURES 1 – 4 : b). Ventral and dorsal surface of a.a. II, V, IX and XIII ( Figs. 3, 4 View FIGURES 1 – 4 ) with very small specialized sensilla. On the ventral side these sensilla are restricted to an internal latero-apical area and are represented by two different types (a and b). Type a sensilla very thin and not split apically ( Fig. 3 View FIGURES 1 – 4 : a), type b sensilla ( Fig. 3 View FIGURES 1 – 4 : b) very similar to those of the apex of a.a. XIV. Specialized sensilla on dorsal side restricted to an external latero-apical area and are represented by three different types: a and b respectively similar to a and b of ventral side ( Fig. 4 View FIGURES 1 – 4 : a, b) and type c sensilla, similar to type b, but a little bigger and darker (ochreous in color) ( Fig. 4 View FIGURES 1 – 4 : c). Position of specialized sensilla on ventral and dorsal surface of a.a. XIII as in Figs. 3, 4 View FIGURES 1 – 4 respectively. Number and distribution of specialized sensilla on ventral and dorsal sides of a.a. II, V, IX and XIII, as in Table 2.
Ventral Dorsal Figs. a b a b c
II – 2–3 – 2–4 –
V 1 4 1 5–6 –
IX 1 7 1 3 7
XIII 1 5 1 14 6 3, 4 Cephalic plate. Distinctly longer than wide (length/width ratio ca. 1.53: 1), without a distinct frontal sulcus. Posterior region somewhat narrower than the anterior; sides nearly straight to slightly convex, curving in at the ends; anterior margin convex at middle, slightly concave at level of bases of the antennae; posterior margin straight. Shape and chaetotaxy as in Fig. 5 View FIGURES 5 – 10 .
Clypeus. With one central seta in front of the clypeal area, one seta located on it ( Fig. 7 View FIGURES 5 – 10 ), and posterior to the latter 3 + 2 setae distributed at both sides of the middle line ( Fig. 6 View FIGURES 5 – 10 ). Clypeal area well developed with surface minutely punctuate or granulate, not areolate ( Fig. 7 View FIGURES 5 – 10 ).
Labrum. Mid-piece unpigmented, small, with ca. 8 short slightly sharp pointed teeth; side-pieces with 21 + 20 hyaline filaments of variable sizes ( Fig. 8 View FIGURES 5 – 10 ).
Mandible. With shape as in Fig. 9 View FIGURES 5 – 10 , pectinate lamella with ca. 31 hyaline teeth.
First maxillae. With well developed lappets on coxosternite and telopodites, relative size as in Figs. 10 View FIGURES 5 – 10 , 11 View FIGURES 11 – 19 . Coxosternite devoid of setae; coxal projections subtriangular, round tipped and provided with 11 + 8 setae ( Fig. 10 View FIGURES 5 – 10 ). Apical article of telopodites with 12 + 13 setae on ventral side ( Fig. 10 View FIGURES 5 – 10 ), and 2 + 2 small sensilla on dorsal side.
Second maxillae. Coxosternites medially joined through a narrow, hyaline and non-areolate membranous isthmus only ( Fig. 10 View FIGURES 5 – 10 ), provided with 12 + 12 setae distributed as in Fig. 10 View FIGURES 5 – 10 . Metameric pores accompanied by a sclerotized rim ( Fig. 10 View FIGURES 5 – 10 : c; Fig. 12 View FIGURES 11 – 19 : a). Apical claw of telopodites well developed ( Figs. 10 View FIGURES 5 – 10 , 13, 14 View FIGURES 11 – 19 ). Chaetotaxy of coxosternites and telopodites as in Figs. 10 View FIGURES 5 – 10 , 13 View FIGURES 11 – 19 .
Forcipular segment (similar to paralectotype A female). When extended the telopodites attaining the end of the a.a. II ( Fig. 40 View FIGURES 40 – 44 ). Forcipular tergite trapeziform, with anterior and posterior margins respectively covered by the cephalic plate and the tergite of the first leg-bearing segment ( Fig. 41 View FIGURES 40 – 44 : a); chaetotaxy represented by 16 + 19 setae with relative size and distribution as sin Fig. 41 View FIGURES 40 – 44 . Coxosternite without chitin-lines, middle part of anterior border slightly concave, provided with 1 + 1 slightly pigmented denticles bearing one dorsal seta; aspect and relative size as in Figs. 40, 42 View FIGURES 40 – 44 . Telopodites: medial edge of trochanteroprefemur with two teeth, both deeply pigmented, the proximal one smaller than the distal ( Figs. 40, 42 View FIGURES 40 – 44 ). Femur and tibia without denticles. Tarsungulum basally with a well developed and deeply pigmented subtriangular tooth ( Figs. 40, 43 View FIGURES 40 – 44 ); medial edge of tarsungulum not serrate ( Figs. 40, 43 View FIGURES 40 – 44 ). Relative size of poison glands as in Fig. 40 View FIGURES 40 – 44 : a, calyx of poison gland subtriangular in shape ( Fig. 43 View FIGURES 40 – 44 : b; Fig. 44 View FIGURES 40 – 44 : a). Chaetotaxy of coxosternite and telopodites as in Fig. 40 View FIGURES 40 – 44 .
Metasternites of leg-bearing segments 1 to penultimate. With a distinct median longitudinal sulcus along all the body length, areolation of its surface as in Figs. 19 View FIGURES 11 – 19 , 23 View FIGURES 20 – 25 . Pores present in an uninterrupted series from metasternite 1 to penultimate inclusive. Metasternite 1 with only one pore ( Fig. 15 View FIGURES 11 – 19 ); remaining metasternites with well developed pore-fields divided in two main areas, which are subsymmetrical on metasternites 2, 4–8, 11–48 ( Figs. 16, 18, 19 View FIGURES 11 – 19 , 22–29 View FIGURES 20 – 25 View FIGURES 26 – 36 ), and asymmetrical on metasternites 3 ( Fig. 17 View FIGURES 11 – 19 ), 9 ( Fig. 20 View FIGURES 20 – 25 ), 10 ( Fig. 21 View FIGURES 20 – 25 ). Metasternites 4 ( Fig. 18 View FIGURES 11 – 19 ), and 25 ( Fig. 24 View FIGURES 20 – 25 ) with an additional small group of pores located on the posterior left side; metasternites 8 ( Fig. 19 View FIGURES 11 – 19 ), and 45 ( Fig. 26 View FIGURES 26 – 36 ) with a similar group of pores on the posterior right side. Number of pores on selected metasternites as follows: metasternite 1 (1); 2 (51 + 46); 3 (27 + 54); 4 (77 + 69); 8 (8 + 98 + 97); 9 (50 + 185); 10 (136 + 33); 11 (88 + 100); 13 (100 + 109); 25 (28 + 41 + 9); 35 (35 + 42); 45 (4 + 24 + 40); 46 (42 + 45); 47 (43 + 37); 48 (35 + 36). Chaetotaxy of metasternites, shape and relative size of pore-fields as in Figs. 15–29 View FIGURES 11 – 19 View FIGURES 20 – 25 View FIGURES 26 – 36 .
Legs (pair 1 to penultimate). First pair shorter than the second in the proportion ca. 0.88: 1. Chaetotaxy similar throughout the whole body length ( Figs. 30–34 View FIGURES 26 – 36 ). Each claw with an anterior and a posterior spine, the anterior ( Figs. 35, 36 View FIGURES 26 – 36 : a) bigger and similar in color to the claw; posterior spine ( Figs. 35, 36 View FIGURES 26 – 36 : b) minute and pale in color.
Ultimate leg-bearing segment. Intercalary pleurites absent at both sides of the ultimate pretergite; ultimate presternite not divided along the sagittal plane; length/width of metatergite 0.76: 1; length/width of metasternite 0.55: 1. Shape and chaetotaxy of metatergite and metasternite as in Figs. 37, 38 View FIGURES 37 – 39 . Coxopleura slightly protruding at distal-internal ventral ends, setae small and numerous distributed on the internal ventral area, the remaining coxopleural surface with few larger setae ( Figs. 37, 38 View FIGURES 37 – 39 ). Each coxopleuron with all coxal organs grouped in a cluster opening on the membrane between coxopleuron and metasternite, partially or totally covered by the latter ( Figs. 38, 39 View FIGURES 37 – 39 ). Each cluster with ca. 20–25 organs arranged as in Figs. 38, 39 View FIGURES 37 – 39 . Ultimate legs moderately inflated, telopodites composed of six articles. Ratio of length of telopodites of ultimate legs/length of metasternite ca. 4.65: 1. Shape and chaetotaxy of ultimate legs as in Figs. 37, 38 View FIGURES 37 – 39 . Ultimate pretarsus unguiform, relatively smaller than those of the preceding legs, bearing a single internal very small, and hyaline spine ventro-basally (similar to paralectotype A female, Fig. 53 View FIGURES 45 – 53 : a).
Postpedal segments. Intermediate tergite with posterior margin strongly convex, bearing numerous setae ( Fig. 37 View FIGURES 37 – 39 ); intermediate sternite distinct, with posterior border concave, posterior border of first genital sternite convex ( Fig. 38 View FIGURES 37 – 39 ). Gonopods uniarticulate, relatively small, not separated on the middle line ( Fig. 38 View FIGURES 37 – 39 ). Anal organs absent.
Male. Unknown.
Variation. Disposition of ventral pores in lectotype female and paralectotype A female reveals the following intraspecific variation (traits in the latter are given in parentheses): Metasternite of first leg-bearing segment with a single pore, Fig. 15 View FIGURES 11 – 19 (with a group of three pores, Fig. 45 View FIGURES 45 – 53 ); most of pore-fields on metasternites 2 to penultimate divided in two subsymmetrical areas, Figs. 16, 18, 19 View FIGURES 11 – 19 , 22–29 View FIGURES 20 – 25 View FIGURES 26 – 36 , and a few divided in two asymmetrical areas, Figs. 17 View FIGURES 11 – 19 , 20, 21 View FIGURES 20 – 25 (all divided in two subsymmetrical areas, Figs. 46–51 View FIGURES 45 – 53 ); a few metasternites bearing an additional small group of pores located on their left or right posterior sides, Figs. 18, 19 View FIGURES 11 – 19 , 24 View FIGURES 20 – 25 , 26 View FIGURES 26 – 36 (all metasternites devoid of additional groups of pores, Figs. 45–51 View FIGURES 45 – 53 ). (Shape of divided pore-fields of paralectotype B female similar as to paralectotype A female).
All other characters without significant variation.
Remarks. Plateurytion mundus was inadequately described by Chamberlin. The original description does not refer to a specimen in particular, nor does it specify the sex of the studied specimens. It only includes three not accurate drawings (cephalic plate; first maxillae; coxopleura and metasternite of ultimate leg-bearing segment showing coxal organs); and completely lacks information on pilosity of the antennae; kind and number of specialized sensilla of a.a. II, V, IX and XIII; shape of mandibles; anterior and posterior limits of ventral pore-field series; shape and relative size of pore-fields; shape of postpedal segments; etc.
In his original description Chamberlin states “coxae of second maxillae broadly and completely united at middle”, but the coxosternites are medially joined through a narrow, hyaline and non-areolate membranous isthmus only ( Fig. 10 View FIGURES 5 – 10 ). About the labrum, the author says “median piece small, transversally subelliptic, without teeth on caudal margin”, but ca. 8 distinct short teeth are present.
The adult (and mated) condition of the three female type specimens is indicated by the presence of spermatozoa in both spermathecae, located at level of the antepenultimate leg-bearing segment.
In the preceding redescription, the forcipular segment is described after the paralectotype A female, because in the lectotype the left forcipular telopodite is missing. Both ultimate legs are incomplete in the lectotype, therefore an ultimate leg of the paralectotype A is illustrated including a detail of the claw-like ultimate pretarsus.
Type locality. CHILE: Region IX (Araucanía region): Cautín province: 35 km E of Temuco.
Known range. Only known from the type locality. (See Fig. 110 View FIGURE 110 ).
Remarks. According to the biogeographical regionalization of the Andean Region proposed by Morrone (2015), the geographical distribution of this species corresponds to the "Maule province" (Sub-Antarctic subregion).
TABLE 1. Comparative matrix of morphological traits for Plateurytion mundus (Chamberlin, 1955) and P. zapallar (Chamberlin, 1955). (Characters of P. mundus from lectotype female, paralectotype A female, and paralectotype B female; those of P. zapallar come from lectotype male, paralectotype female, and non-type specimens mentioned in " Other material examined ").
P. mundus | P. zapallar | |
---|---|---|
Number of leg-bearing segments | ♀: 49, 51 ♂:? | ♀: 47, 49, (probably 51), 53 ♂: 47, 49, 51 |
Body length | 35–45 mm (♀) | 27 mm (♂) 28 mm (♀) |
Maximum body width | ca. 1.9 mm (♀) | ca. 1.3 mm (♂) |
Number of claviform sensilla on external border of a.a. XIV | ca. 29 | ca. 13 |
Number of type b and c specialized sensilla on dorsal side of a.a. XIII | type b: ca. 14 type c: ca. 6 | type b: ca. 3 type c: ca. 1 |
Teeth of labrum mid-piece | Short slightly sharp pointed (Fig. 8) | similar to the long filaments of the sidepieces (but thinner and smaller, Figs. 63, 64) |
Number of ventral setae on second article of telopodites of first maxillae | ca. 12–13 | ca. 4–7 |
Number of ventral setae on third article of telopodites of second maxillae | ca. 11–15 | ca. 5–6 |
Middle part of anterior border of forcipular coxosternite conspicuously notched and strongly concave | no (slightly concave, Figs. 40, 42) | yes (Figs. 67, 69) |
Ventral pore-fields | undivided on metasternite 1, divided in two areas on metasternites 2 to penultimate (Figs. 15–29, 45–51) | undivided on metasternites 1 to ca. 15, divided in two areas on remaining metasternites including the penultimate (Figs. 73–85) |
Anterior accessory spines of claws of walking legs | pigmented (Figs. 35, 36: a) | unpigmented (Figs. 92, 93: a) |
Number of organs in each cluster of coxal organs in the coxopleura of the ultimate leg-bearing segment | ca. 20–25 (Fig. 39) | ca. 8–11 (Figs. 96, 104, 109) |
CAS |
California Academy of Sciences |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Pachymerium mundus
Pereira, Luis Alberto 2015 |
mundus
Pereira 2008: 56 |
Bonato 2007: 6 |
Eurytion mundum:
Pereira 2006: 167 |
Foddai 2000: 75 |
Crabill 1968: 231 |
Chilerium mundum
Chamberlin 1955: 23 |