Mylassa obliquata ( Suffrian, 1863 )

Sassi, Davide, 2025, Taxonomic revision of the South American genus Mylassa Stål, 1867 (Coleoptera: Chrysomelidae: Cryptocephalinae) with the description of eight new species, Zootaxa 5683 (3), pp. 301-359 : 315-325

Mylassa obliquata ( Suffrian, 1863)

( Fig. 3 ; Figs. 12c ; 15g –i ; 20a–b ; 24a–b ; 26c )

Cryptocephalus obliquatus Suffrian, 1863: 175 (original description); Clavareau, 1913: 167 (catalogue).

Mylassa obliquata Jacobson, 1924: 257 (catalogue); Monrós, 1949: 516 (redescription); Agrain et al. 2017: 61 (catalogue).

Mylassa chachallaoi Monrós, 1949: 513 (original description); Roig-Juñent, 2004: 107 (catalogue); Agrain et al. 2017: 60 (catalogue). Syn. nov.

Types. Suffrian (1863) did not mention the number of the studied specimens but reported that he saw male(s) from Valdivia in coll. Sturm, and females from coll. Riehl, Deyrolle e Haag. This material was sought in public collections currently housing parts of the aforementioned collections (ZSM, BMNH, SDEI, MLUH and PZCM). Two specimens, females, to be considered part of the original type series studied by Suffrian, were located at BMNH and SDEI. The former of these (BMNH) appears severely damaged and incomplete, lacking the features necessary for confident identification, while the latter (SDEI) is female. Additionally, four specimens, one male and three females, are housed at MLUH in the Suffrian collection. In this case, as is customary in Suffrian’s collection, specimens lack labels indicating their provenance. However, it is more than reasonable to assume that all material in his personal collection, unless there are clear contrary indications, consists of retained specimens from the original series used for his research. Moreover, these specimens undoubtedly correspond to Suffrian’s concept of the species he described. For this reason, the specimens at MLUH have been considered syntypes. Since the only available male is among them, it has been designated as the lectotype. It should be noted that I. S. Askevold also selected and labelled this specimen as lectotype in 1988, but the nomenclatural act was never published. Type designation was made as follows, in order to stabilize the epithet. LECTOTYPE (by present designation): (MLUH), ♂, pinned // “obliquatus m. Chile ” [White label, handwritten. The label is not attached to the individual specimen but placed at the beginning of the specimens’ row] // “19003” [White label, handwritten] // “ Lectotype ♂ Cryptocephalus obliquatus Suffrian design. I. S. Askevold 1988” [Red label, partly handwritten] // “ Mylassa crassicollis (Blanch.) det. I. S. Askevold 1988” [White label, partly handwritten] // “ Mylassa obliquata ( Suffrian, 1863) ( Cryptocephalus obliquatus ) LECTOTYPUS D. Sassi des.” [red label, printed]. PARALECTOTYPES (5): (MLUH), ♀, pinned // “26644” [White label, handwritten] // “ Mylassa crassicollis (Blanch.) det. I. S. Askevold 1988” [White label, partly handwritten]; (MLUH), ♀, pinned // “23924” [White label, handwritten] // “ Mylassa crassicollis (Blanch.) det. I. S. Askevold 1988” [White label, partly handwritten]; (MLUH), ♀, pinned // “94729” [White label, handwritten] // “ Mylassa crassicollis (Blanch.) det. I. S. Askevold 1988” [White label, partly handwritten]; (BMNH), ♀, pinned // “ Chili ” [green label, handwritten] // “Type Suffr coll. Deyrolle” [white label, handwritten] // “Baly Coll.” [white label, printed] // “ Mylassa obliquata Suffr Chili ” [white label, handwritten]; (SDEI), ♀, glued // “ Chili Riehl” [white label, handwritten] // “Coll. Haag” [white label, printed] // “obliquatus Suffr. ” [white label, handwritten] // “SDEI Coleoptera # 303853” [white label, printed]. All paralectotypes were labelled: // “ Mylassa obliquata ( Suffrian, 1863) ( Cryptocephalus obliquatus ) PARALECTOTYPUS D. Sassi des.” [red label, printed] //.

Monrós (1949) described M. chachallaoi based on 21 specimens available for his study, some of which, including the holotype, kept in his personal collection, which is now housed at USNMNH, and others in IFML. Again, thanks to the courtesy of Alexander Konstantinov (USNMNH) it has been possible to confirm presence of holotype in USNMNH. It is labelled as follows: HOLOTYPE: (USNMNH)), ♂, glued, aedeagal median lobe and abdomen glued on a separate card // “ Chile Frutillar Feb. 944 Kuschel” [White label, handwritten] // “Sobre Lomantia [sic] obliqua Kuschel.” [White label, handwritten] // “ Mylassa chachallaoi mihi F. Monrós det. 1949” [Pink label, partly handwritten] // “TypeNo.65279 U.S. N.M.” [Red label, partly handwritten] // “? Holotype OH,3” [White label, handwritten] // “USNMENT 00911231” [White label, printed] // “ Mylassa chachallaoi Monrós, 1949 HOLOTYPUS D. Sassi vidit.” [red label, printed] // “ Mylassa obliquata Suffrian, 1863 D. Sassi det. 2025 [White label, printed] //. In addition, thanks to the courtesy of Emilia Constanza Perez (IFML) and, again, Alexander Konstantinov (USNMNH) it was possible to confirm presence of 4 paratypes in IFML and 4 paratypes in USNMNH. I had the chance to examine numerous specimens, including some paratypes from material studied by Monrós. From my analysis, it becomes evident that Monrós, without having studied types of M. obliquata , had formed an inaccurate understanding of this species. He erroneously assigned specimens belonging to an unpublished taxon, which is described herein as M. monrosi , to M. obliquata , and subsequently redescribed the latter as a new species, naming it as M. chachallaoi . Indeed, the two species share obvious similarities, and lack of examination of type material can result in misinterpretation. It is noteworthy, however, that Suffrian aptly described a potentially decisive character: distinct conformation of apex of anterior tibiae in males of M. obliquata (“die langen Vorderschienen mit dem unteren Viertel stark einwärts gekrümmt, vor den Enden rhombisch verbreitert und dann noch seitlich in eine spornartige Spitze ausgezogen”). It is surprising that Monrós overlooked this detail. Based on previous considerations, the following new synonymy is proposed here: Mylassa obliquata ( Suffrian, 1866) = Mylassa chachallaoi Monrós, 1949 syn. nov.

Type locality. M. obliquata : Valdivia ( Los Rios, Chile). M. chachallaoi : Frutillar ( Los Lagos, Chile).

Additional material examined. ( 36 specimens). ARGENTINA: Chubut: Parque Nacional los Alerces Río Arrayanes 9.III.1974 (3, MDPC) . CHILE: Araucanía: Curacautín env. 21.I.2005 (3, MSNG) ; Malleco Prov. Parc Nac. Nahuelbuta 1100m 5–8.I.1989 (1, IAPC) . Los Lagos: Petrohué 27.XII.1943 (1, USNMNH) ; Petrohué 25.II.1972 (3, DSPC) ; W of Los Muermos 160m 28.I.2005 (2, MSNG) ; Entre Lagos W of Anticura 12.II.2005 (2, MSNG) . Los Ríos: Niebla Valdivia (1, DSPC) ; Valdivia (1, DSPC) ; E of Lago Ranco 2.II.2004 (6, MSNG) ; NW of La Unión Santa Elisa env. 24.I.2004 (2, MSNG) ; W of La Unión E of El Mirador 27.I.2004 (8, MSNG) . Maule: Bullileo Parral I.1979 (1, IAPC) . “ Chili ” (2, NMPC) .

Additional data from literature and GBIF. (as M. chachallaoi ): ARGENTINA: Chubut: Lake Futalafquen ( Monrós, 1949). Neuquén: PuertoAnchorena Isla Victoria ( Monrós, 1949);Puerto Radal Isla Victoria( Monrós, 1949). CHILE: Los Lagos: Petrohué ( Monrós, 1949); Llanquihue (https://www.inaturalist.org/observations/258076567).

Distribution. Argentina ( Chubut, Neuquén); Chile ( Araucanía, Los Lagos, Los Ríos, Maule).

Biological notes. The species was collected by Monrós (1949) on Lomatia hirsuta subsp. obliqua (Ruiz & Pav.) R. T. Penn. ( Proteaceae ).

Diagnosis. The species is morphologically similar to the quite variable Mylassa crassicollis . As Monrós (1949) already pointed out, the red patch covering the entire base of the elytron and extending backward along the lateral margin seems to be rather typical of the species, at least in males. Even when this red chromatic pattern appears scarcely recognizable, it still tends to develop along the margins of the elytron; hence, the course of the red elytral design remains rather distinct from that of M. crassicollis , typically more transverse and zigzagging. Additionally, dimensions in M. obliquata are slightly larger, and the tooth-like process at the distal ending of the anterior tibiae is noticeably sturdier. In the median lobe of the aedeagus, the apex is more pointed with a thinner edge, and the longitudinal median ridge on the ventral surface is less pronounced. The setigerous lamellae are almost squareshaped and therefore substantially symmetrical along the apical edge. In some specimens, usually females, exhibiting reduced red elytral coloration, the chromatic pattern is practically identical to that of M. monrosi . In this instance, however, the denser and more robust punctation of the pronotum, which is slightly less bulging, and the shorter antennomeres in the latter species allows for effective discrimination.

Description of male. Habitus in Figs. 3a–b, 3m . BL = 3.8–4.2 mm, BW = 2.4–2.5 mm, PL = 1.4–1.8 mm, PW = 2.2–2.4 mm. Interocular distance 14.3–15.8 % of BL.

Head totally black. Labrum dark brownish. Vertex and frontoclypeal surface covered with recumbent setae and minute punctation, sparser on clypeal area. Mid-cranial suture not clearly detectable. Eyes small, scarcely bulging, only shallowly notched on inner margin with upper lobes well separated from each other. Ocular lines shallow, visible along upper lobe, adhering to ocular rim. Antennae long, almost reaching elytral apex when bent backwards, antennomeres slender, dark brown (2–3 slightly lighter), bright, scarcely setose; antennomeres 4–10 subcylindrical, scarcely different in shape; length nearly uniform.

Pronotum totally black, regularly convex, bulging. Lateral margins narrow, not visible from above, weakly and regularly arched with maximum width at hind angles. Posterolateral impressions short and shallow, close to posterior margin. Pronotal surface covered with close, regularly distributed fine punctation and sparse, appressed whitish setae. Posterior lobe wide, slightly convex with apex truncated in straight line.

Scutellum black, triangular, not raised, very minutely punctured, surface covered with short, appressed setae.

Elytron black with transverse band covering basal margin up to humeral callus, extended backward parallel to lateral margin up to midline. Such band sometimes medially reaching anterior end of suture.Apex of elytron covered with red spot as well. Usually, a further small lengthened red spot at middle of disc. Elytral outline cylindrical, slightly flattened behind scutellum, with sides almost parallel or slightly convergent toward apex. Lateral margins narrow, not visible from above. Scutellar area not raised. Humeral callus scarcely prominent, not punctured. Elytral punctures arranged in almost regular rows, well impressed, distinguishable also towards apex. All elytral surface covered with appressed or semi-erect setae, partly whitish, partly blackish. Epipleura narrow, with concave, rugulose surface.

Pygidium black, covered by fine punctures and rather thick whitish setae.

Ventral surface black, matt, covered with long appressed whitish setae, except scarcely setose, shiny posterior part of hypomera. Prosternal process wide, transverse, transversely depressed behind midline and raised at sides; sides with long, sharp denticle at middle; surface minutely punctured, covered with thick erect setae; posterior margin almost straight.

Legs totally black. Anterior tibiae bent inwards before apex, with strong spur-like process on inner end. Apex of median tibiae enlarged, with robust blunt, subapical tooth-like process on inner side.

Fifth abdominal ventrite devoid of median depression along posterior margins. Posterior margin of fifth abdominal ventrite straight.

Median lobe of aedeagus ( Figs. 15g –i ) stubby, weakly pointed at apex. Aedeagal ventral surface strongly concave, with only hint of longitudinal carina. Setose depressions slender, shallow, scarcely delimited. Setigerous lamellae large, triangular, bearing long, thick setae.

Female. BL = 4.4–4.6 mm, BW = 2.8–2.9 mm, PL = 1.8–1.9 mm, PW = 2.7 mm. Interocular distance 17.4–18.2 % of BL.

Female differs in lacking fore and median tibial modifications, in slenderer and shorter fore tarsi, in the shorter antennae, in shape of pronotal posterior lobe, which is proportionally wider.

Fifth abdominal ventrite in female with large, shallow, anteriorly tapered pit with a flat, scarcely setose base.

The vasculum of spermatheca ( Figs. 24a–b ) is scarcely pigmented, slender, hook-shaped, with proximal and distal lobes particularly slender, approximately of same length. Ampulla lengthened, cylindrical and weakly pigmented. Duct insertion and sperm gland insertion fully separate, the latter sitting at proximal end of the ampulla. Duct is short, coiled along its distal section. The rigid and opaque sleeve surrounding proximal section is curved at insertion on the bursa copulatrix.

Remarks. For this species, as for others housed in London, Berlin, and Washington, I. S. Askevold made interesting observations and left handwritten notes on labels attached to specimens in the years 1988 and 1998. Unfortunately, he never published the results of his research, but his notes provided useful insights in formulating some of my taxonomic evaluations. In the case of species in question, Askevold correctly assessed appropriateness of considering the male preserved in Halle as the name-bearing type; however, it should be noted that at that time (1988), he considered Mylassa obliquata a junior subjective synonym of M. crassicollis . He later changed his opinion (1998), coming to regard M. obliquata as a distinct species from M. crassicollis but considering that this name should be considered a junior synonym of Pachybrachis concinnus Philippi, 1859 . The observation is certainly interesting, and it is indeed very likely that P. concinnus is actually a Mylassa . However, the description of P. concinnus appears too vague and ambiguous, and it might apply to most of the species belonging to the genus Mylassa , including some described as new in this work. Unfortunately, despite thorough research, it was not possible to locate type material of P. concinnus in either European or South American institutions, and it is likely that this material should be considered lost. Therefore, at least with the current state of knowledge, it does not seem possible to use this name in the present work.

Mylassa pectinicornis ( Suffrian, 1866)

( Fig. 4 ; Figs. 12d ; 16a–c ; 20c–d ; 24c–d ; 26d )

Cryptocephalus pectinicornis Suffrian, 1866: 16 (original description); Clavareau, 1913: 172 (catalogue); Blackwelder, 1946: 646 (catalogue).

Mylassa pectinicornis Jacobson, 1924: 257 (catalogue); Monrós, 1949: 520 (redescription); Roig-Juñent, 2004: 107 (catalogue); Schöller, 2008: 96 (taxonomic notes); Agrain et al. 2017: 61 (catalogue).

Types. Suffrian (1866) clearly states a single male was available for description, and it came from the Clark collection. The possible type must therefore be in London (where the Clark collection is housed) and possibly in Halle, where Suffrian’s collection is kept, reasonably consisting of material retained by him at the end of his study. The examination of the collections has indeed revealed two specimens (in BMNH and in MLUH) that correspond to these characteristics. The specimen in MLUH bears a label, handwritten by I. Askevold, designating it as holotype, but it should be noted that Askevold never published his observations on this species. However, there is a closer correspondence between the original description and the elytral colour pattern, which is meticulously depicted by Suffrian, of the specimen housed in London. For this reason, it was considered more appropriate to identify such specimen preserved in BMNH as the holotype of the species. Surprisingly, the usual label “67.56” accompanying specimens from the former Clark collection at BMNH was not found. This alphanumeric code typically denotes the accession number and year of acquisition of the material. This label is so ubiquitous that it can be considered the official “signature” of the Clark collection. Conversely, as reported by Michael Geiser (Geiser, personal communication, 2024), shape of the printed label “TYPE” is characteristic of Alexander Fry’s collection but is also found on many specimens from Hamlet Clark’s collection. Additionally, according to Michael Geiser there is evidence that Clark and Fry frequently exchanged specimens and corresponded with each other. Alexander Fry was a businessman in Rio de Janeiro during the 1850s and 1860s, overlapping with Clark’s travels there, suggesting a plausible collaboration in collecting. The label “ Chili ” appears to be written in A. Fry’s distinct handwriting; one intriguing detail is that the “ Chili ” label is trimmed to a smaller size (a practice often seen with specimens received from Fry by H. Clark). Fry’s own specimens from Chile have slightly larger locality labels. Furthermore, the blue label “60 pectinicornis” appears to be in H. Clark’s handwriting. Notably, this specimen was positioned adjacent to a female specimen in the collection bearing the classic “67.56” label. These interesting insights supplied by M. Geiser, while not totally decisive, are compelling. Based on this evidence, I am reasonably confident that the specimen labelled “TYPE” is indeed from Hamlet Clark’s collection and may therefore be considered a type specimen for M. pectinicornis . Clark likely received it from A. Fry and subsequently sent it to Suffrian for identification, a practice he often followed with his Cryptocephalinae . Type designation was made as follows, in order to stabilize the epithet. HOLOTYPE (by present identification): (BMNH), ♂, pinned // “ Chili ” [White label, handwritten] // “TYPE” [White label, printed] // “ Syntype ” [White, blue bordered label, printed] // “60 pertinicornis” [Blue label, handwritten] // “60” [Blue label, handwritten] // “ Mylassa pectinicornis ( Suffrian, 1866) ( Cryptocephalus pectinicornis ) HOLOTYPUS D. Sassi det.” [red label, printed].

Type locality. “ Chile ” .

Additional material examined ( 70 specimens). ARGENTINA: Chubut: Esquel Lake Verde 17.II.1949 (4, USNMNH) . Neuquén: Chapelco 1000m 28.XII.1951 (1, NHMB) ; Lake Correntoso I.1943 (1, USNMNH) . Río Negro: San Carlos de Bariloche 29.XI.1961 (1, HNHMB) ; Lake Moreno 25.I.1949 (1, USNMNH) ; El Bolsón 02.XII.2003 (1, MDPC) . CHILE: Araucanía: Pucón Villarrica XII.1994 (1, DSPC) ; 22.9 km E Pucón 870m 1.XII.2013 (3, NMPC) ; Volcán Quetrupillán Parque Nacional Villarrica (5, LSPC); S of Melipeuco 23.I.2004 (34, MSNG & DSPC) ; Las Raíces Cautín XII.1994 (2, DSPC) ; Pehuenco Parque National Nahuelbuta, 25–28.XI.2013 (1, NMPC) . Bío Bío: Ralco XI.1994 (1, MSNM) . Los Rios: Panguipulli N of Enco 20.I.2004 (1, MSNG) . Maule: Corralones San Clemente 25.XI.2003 (1, MSNG) ; Romehual, Cordillera Parral XI.1960 (1, DSPC) ; Fundo Malco, Cordillera Parral XII.1956 (1, DSPC) ; Talca Vilches Alto Talca prov. 9.X.1995 (1. DSPC) . Ñuble: Las Trancas E Chillán XI.1990 (1, DSPC) ; Las Trancas 1/15.XII.75 (1, IAPC); Chillán 12.I.1988 on Drimys winteris (2, IAPC) . Santiago (?): “Stgo” XII.1987 (5, IAPC) . The latter record, due to its extremely vague locality indication, is not shown on the distribution map ( Fig. 26d ), as it would depict an isolated and highly imprecise station located over 200 km north of the confirmed range. This record is considered to require further confirmation.

Additional data from literature. ARGENTINA: Chubut: Lake Futalafquen ( Monrós, 1949); Lake Verde ( Monrós, 1949). Neuquén: San Martín de los Andes ( Monrós, 1949); Lake Correntoso ( Monrós, 1949). Río Negro: San Carlos de Bariloche ( Monrós, 1949); Isla Victoria ( Monrós, 1949).

Distribution. Argentina ( Chubut, Neuquén, Río Negro); Chile ( Araucanía, Biobío, Los Rios, Maule, Ñuble).

Biological notes. Collected on Lomatia hirsuta subsp. obliqua (Ruiz & Pav.) R. T. Penn. ( Proteaceae ) ( Monrós, 1949). Among examined specimens, one bears a label indicating Drimys winteri J.R.Forst. & G.Forst. ( Winteraceae ) as possible host plant.

Diagnosis. Mylassa pectinicornis is the species with, on average, the larger size; only M. frigens , M. obliquata , M. monrosi and M. crassicollis can sometimes reach similar body length. However, M. pectinicornis is easily recognizable by the striking characteristic in males of the apical antennal segments strongly modified to form a comb-like structure. Among females with entirely red elytral coloration, only M. rubronotata may resemble it, but in the latter species, the size is significantly smaller, and the shape is more robust. Females with darker elytral coloration are also well distinguished from other species, either because they are entirely black or because the yellow pattern is limited to a thin border along the elytral outline.

Description of male. Habitus in Figs. 4a–c . BL = 4.2–4.6 mm, BW = 2.3–2.6 mm, PL = 1.5–1.9 mm, PW = 2.2–2.5 mm. Interocular distance 16.7–17.4 % of BL.

Head totally black. Vertex and frontoclypeal surface slightly depressed on vertex and between eyes; mid-cranial suture not clearly detectable; surface almost devoid of pilosity but with well-impressed, close, regularly distributed punctation. Eyes small, scarcely bulging, only shallowly notched on inner margin with upper lobes well separated from each other. Ocular lines not detectable. Antennae long, almost reaching elytral apex when bent backwards, antennomeres robust, black, sometimes with lighter patches, especially on basal segments, minutely setose; antennomeres 4–7 slightly flattened, scarcely different in shape; antennomere 8 strongly enlarged at apex toward midline in acute denticle; antennomeres 9–11 shell-shaped, shortened and expanded toward midline as well.

Pronotum totally black, regularly convex, bulging. Lateral margins narrow, not visible from above, regularly arched so that maximum width at about middle. Posterolateral impressions short and very weakly impressed, close to posterior margin. Pronotal surface covered with close, regularly distributed fine punctation and sparse, short, semi-erect setae. Posterior lobe short, rather slender, slightly convex with apex truncated in straight line.

Scutellum black, triangular, not raised, very minutely, closely punctured. Surface covered with short setae.

Elytron totally black. Elytral outline cylindrical, rather slender, regularly convex, with sides almost parallel or slightly convergent toward apex. Lateral margins narrow, not visible from above. Scutellar area not raised. Humeral callus prominent, not punctured. Elytral surface matt, with fine punctures arranged in scarcely visible rows and often covered with shallow transverse rugosity. All elytral surface covered with rather short, sparse, semi-erect setae. Epipleura narrow, with plane or slightly concave surface.

Pygidium black, matt, covered by fine punctures and rather thick, appressed, whitish setae.

Ventral surface black, matt, with sparse, appressed, whitish setae, except scarcely setose, shiny posterior part of hypomera. Prosternal process wide, square, depressed at centre and raised along sides; sides with sharp denticle at middle; surface coarsely punctured, covered with thick appressed setae; posterior margin straight.

Legs completely black. Anterior tibiae essentially straight, but apical half broadened inwards to form a laminar, angulate expansion. First tarsomere of anterior legs strongly elongated, laterally compressed, tapered. Median tibiae expanded at apex, without tooth-like process.

Abdomen in lateral view strongly concave. Fifth abdominal ventrite devoid of median depression along posterior margins. Posterior margin of fifth abdominal ventrite straight.

Median lobe of aedeagus ( Figs. 16a–c ) short, squat, terminated by almost truncated apex. Ventral surface strongly concave, crossed by thin, weakly raised, median longitudinal carina. At apex two long, slender setigerous lamellae, each bearing thick setose tuft apically directed.

Female. Habitus in Figs. 4f–g . BL = 3.9–4.4 mm, BW = 2.3–2.7 mm, PL = 1.6–1.8 mm, PW = 2.2–2.5 mm. Interocular distance 17.9–18.2 % of BL.

Females differ in lacking anterior and median legs modification, in shorter outline and slightly larger interocular distance. Antennae do not exhibit the strong modification present in males, but antennomeres 8–10 are fairly shortened and flattened. Elytron is usually totally reddish, but individuals with black elytral colour pattern are quite common. In this latter case, anterior, lateral and apical margins are totally or partly yellowish.

Fifth abdominal ventrite in females with shallow pit with a flat, bald, not punctured base.

The vasculum of spermatheca is slender, hook shaped ( Figs. 24c–d ). The lobes of vasculum are not swollen, with proximal one slightly longer. Ampulla is long, subcylindrical and weakly pigmented. Duct insertion and sperm gland insertion fully separate, the latter sitting at proximal end of ampulla. Distal, coiled section of duct is particularly short, while proximal section surrounded by rigid sleeve is about equal in length or even longer than distal one.

Mylassa rubronotata (Blanchard, 1851)

( Fig. 5 ; Figs. 13a ; 16d–f ; 19a–b ; 24e–f ; 26e )

Pachybrachys rubronotatus Blanchard, 1851: 540 (original description).

Cryptocephalus rubronotatus Suffrian, 1863: 177 (redescription); Clavareau, 1913: 181 (catalogue); Blackwelder, 1946: 646 (catalogue).

Mylassa rubronotata Jacobson, 1924: 258 (catalogue); Monrós, 1949: 505 (redescription).

Mylassa socia Stål, 1857: 60 (original description); Jacobson, 1924: 257 (catalogue); Monrós, 1949: 501 (redescription). Syn. nov.

Cryptocephalus socius Suffrian, 1863: 179 (redescription); Clavareau, 1913: 187 (catalogue).

Pachybrachys aurantipennis Brèthes, 1929: 208 (original description); Monrós, 1949: 504 (as junior synonym of Mylassa socia , redescription).

Types. Blanchard (1851) did not mention number of studied specimens; however, he pointed out more than one single locality for Pachybrachys rubronotatus (“ Santiago , Santa Rosa etc.”). In MNHN, in an old box labelled: “Typi Blanchard Chile ” and “ Types de Blanchard Amerique , five syntypes are located: four females and one male (the latter in very poor condition). One female had previously been identified and labelled as lectotypus by I. S. Askevold, but the nomenclatorial act had never been published. The other four specimens bear a round green label without any markings. Only one of these specimens bears an additional handwritten white label stating “ S. Jago S. Rosa ”, which corresponds perfectly to information provided in the original description. Additionally, in a second box of the “historical” collection, seven more specimens were found, divided into two series, with a comprehensive green label placed at bottom of box reading: “ C. rubronotatus Cat. mus. Chili M. Gay ” [green label, handwritten]. Furthermore, four of them bear a round white label stating “ Mr. Gay Chili ” [round white label, handwritten], one bears a round white label reading “67 94” [round white label, handwritten], and the other two have no label. All of these specimens have been considered part of the type series as well. Type designation was made as follows, in order to stabilize the epithet. LECTOTYPE: ( MNHN), ♀, pinned // “ Pachybrachys rubronotatus Bl. ” [white label, handwritten] // “Museum Paris Chili Gay 15-43” [round white label, printed] // “15 43” [white label, handwritten] // “Type” [red label, printed] // “ Mylassa rubronotata (Blch.) I. S. Askevold 1987 ” [white label, partly handwritten] // “ Lectotype Pachyrachys rubronotatus Blch. design. IS Askevold 1988” [red label, partly handwritten] // “ Mylassa rubronotata (Blanchard, 1851) ( Pachybrachys rubronotatus ) LECTOTYPUS D. Sassi des.” [red label, printed] //. PARALECTOTYPES (11): All paralectotypes were labelled: // “ Mylassa rubronotata (Blanchard, 1851) ( Pachybrachys rubronotatus ) PARALECTOTYPUS D. Sassi des.” .

Although a male is available in the type series, a female has been chosen as lectotype because it better corresponds to the description given by Blanchard, thus allowing us to adhere more closely to Blanchard’s understanding of the species he described.

Stål (1857) did not mention number of studied specimens of Mylassa socia , but a single syntype was found in SMNH. Type designation was made as follows, in order to stabilize the epithet. LECTOTYPE (by present designation): (SMNH), pinned // “ Chili ” [White label, printed] // “Fairm.” [White label, handwritten] // “Typus” [Red label, printed] // “socius Stål ” [White label, handwritten] // “ Mylassa socia Stål 1857 LECTOTYPUS D. Sassi des.” [red label, printed]. However, careful examination of available material does not reveal differences between specimens assignable to this taxon and those belonging to M. rubronotata . Different elytral coloration, the only character that would be significant according to original descriptions and comparing type specimens, is actually frequently observable, with evident transitional forms, in specimens from the same collection localities. Also, diagnostic characters indicated by Monrós (1949), i.e. vague differences in overall shape and morphology of apex of aedeagus, are not confirmed by my study. Therefore, the following new synonymy is proposed here: Mylassa rubronotata (Blanchard, 1851) = Mylassa socia Stål, 1857 syn. nov.

It should be noted that while in revision of the genus, Monrós (1949) maintained that M. socia and M. rubronotata were certainly two distinct species, he also reported having been able to examine only one male of M. socia , and only a few years later he seems to have harbored doubts regarding this certainty, as material housed in Basel, determined by him, bears the indication: “ Mylassa rubronotata var. socia, Monrós det. 1952”. Additionally, it is interesting to note that Suffrian himself (1863), while keeping the two taxa separate, raises likelihood that M. socia may actually be the male of M. rubronotata .

Regarding Pachybrachys aurantipennis, Brèthes does not indicate number of studied specimens, but reports two different values for body length, so it is reasonable to assume that he examined more than one specimen. Monrós claimed he could see the type, preserved in the Brèthes collection at the Museo Argentino de Ciencias Naturales (MACN). He added that the specimen beared an autographed label with inscription ‘ Pachybrachys aurantipennis — Type!’ and a second label, apparently by the same author, with the name ‘ Cryptocephalus ,’ and stated that it was identical to Mylassa socia . Unfortunately, it appears that currently no specimen of the type series of P. aurantipennis is present in the collections of the MACN (thanks to the kind collaboration of Gastón E. Zubarán, who kindly conducted a thorough search to facilitate my study). The possibility that the specimen mentioned by Monrós has not been returned was also explored, but there is no trace of it even in the collection of this author, now preserved at the USNMNH. Therefore, it is highly probable that the specimen has been lost. Consequently, the synonymy with Mylassa socia , and therefore with M. rubronotata , is accepted based on Monrós account ( Monrós,1949).

Type locality Pachybrachys rubronotatus : “ Chile ” (Despite two less generic localities being present in the original description (Blanchard, 1851) and on a single label, none of the specimens assigned to the type series bears any reliable specific indication of provenance); Mylassa socia and Pachybrachys aurantipennis : “ Chile ”.

Additional material examined ( 377 specimens). CHILE: Biobío: Los Angeles I.1953 (1, USNMNH) ; Contulmo (1, NHMB); Yumbel 300m 19.XI.1985 on Retanilla ephedra (Brongn.) (7, IAPC) . Coquimbo: Los Vilos env. 15.XI.2003 (1, MSNG) . Maule: Cayurranquil W Cauquenes 400m 23–31.I.1981 (1, USNMNH) ; Robleria Linares 23.II.2003 (22, MSNG & MNHUB) ; Curicó Los Morongos X.1994 (1, MSNM) ; 10 km E Curicó 22–31.XII 1997 (1, DSPC) ; Curicó E of Potrero Grande 10.XII.2003 (45, MSNG & MNHUB) ; Curicó 15 km E Potrero Grande 25.XI.2003 (1, DSPC) ; Los Queñes Teno (2, DSPC); Corralones San Clemente 25.XI.2003 (1, MSNG) ; Bäder von Longavi, Parral, (1, MNHUB) . Ñuble: Chillán Las Trancas XII.2003 (2, MSNM) . Santiago: Laguna de Aculeo (52, DSPC) ; Rio Maipo (20, DSPC) ; El Canelo I.1930 & IX.1948 & XII.1948 & XII.1949 & XII.1951 & 6.I.1953 (71, NHMB & USNMNH ; Cajón de Lisboa [Melipilla, Alhué] XII.1989 (3, DSPC) ; Cerro La Obra 900m 9.XII.1986 on Retanilla ephedra (Brongn.) (5, IAPC) ; La Obra 800m 16–25.XII.1986 (7, IAPC) ; La Obra 800m 14–16.XII.1986 (72, IAPC) ; Rancagua Q.La Goyana SE Aculeo 1800m XII.1981 (18, IAPC) ; El Canelo 1977 (14, IAPC); “Santiago” (1, MNHUB) . Valparaíso: “Valparaíso” E. P. Reed B. M. 1934-317 1922 (9, BMNH) ; “Valparaíso” 1922 (2, MNHUB). “D. Ed. Varas Arangua 1921” (20, MSNG) . “ Chile ”: (4, NMPC). “ South America ”: (1, SNMS) .

Additional data from literature. CHILE: Coquimbo: “Coquimbo” (as M. socia ) ( Suffrian, 1863). Los Ríos: Coñaripos (Coñaripe?) Valdivia Prov. ( Monrós, 1949). Santiago: El Canelo; San Jose de Maipo ( Monrós, 1949); Bosque de Santiago (El Bosque?) ( Monrós, 1949); Alhué, Melipilla prov. ( Monrós, 1949).

Distribution. Chile ( Biobío, Coquimbo, Los Ríos, Maule, Ñuble, Santiago, Valparaíso). Indication “Lima” reported by Suffrian (1863) for a specimen from the Kraatz collection appears unreliable, likely due to labelling error. Further confirmation is necessary to consider the species present so far north of its distribution centre.

Biological notes. According to label data, a few specimens examined in this study were collected on Retanilla ephedra (Vent.) Brongn. ( Rhamnaceae ).

Diagnosis. Mylassa rubronotata , along with M. flavolimbata , M. daccordii , M. postmediana , M. longicornis , and M. mirabilis , belongs to the subgroup of smaller-sized species, but it is distinguished from all others by the stockier outline and the significantly more extensive red coloration on elytra. In the latter ones, by contrast, light elytral pattern is limited to two rather small, reddish or yellowish spots, always separated from each other, the first located halfway along outer area of elytra and the second at apex, never extending over more than half the elytral surface. In males of M. rubronotata , antennomeres are stout and slightly flattened; slender and cylindrical in other small-sized species. Additionally, in males, anterior tibiae do not show any particular modifications, as observed in almost all other species of the genus. M. daccordii is an exception, for its males also have unmodified anterior tibiae, but dorsal coloration of the specimens, as said above, is completely different.

Description of male. Habitus in Fig. 5f . BL = 2.5–3.2 mm, BW = 1.6–1.9 mm, PL = 1.0– 1.2 mm, PW = 1.5–1.8 mm. Interocular distance 18.8–20.0 % of BL.

Head totally black. Vertex and frontoclypeal surface covered with fine, regularly distributed punctation and thick, short appressed pilosity, crossed by hollow linear depression, mid-cranial suture not clearly detectable. Eyes small, scarcely bulging, only shallowly notched on inner margin with upper lobes well separated from each other. Ocular lines scarcely impressed, barely visible only along upper ocular margin. Antennae almost reaching elytral clivus when bent backwards, antennomeres robust, minutely setose, 1–5 yellowish, remainders progressively darkened; antennomere 3 short, less than two times as long as the second one; 4–10 robust, slightly flattened, scarcely different from each other in length and shape.

Pronotum totally black, regularly convex, bulging. Lateral margins narrow, not visible from above, almost straight, regularly converging towards anterior margin so that maximum width near basal margin. Posterolateral impressions short and very weakly impressed, close to posterior margin. Pronotal surface covered with close, regularly distributed fine punctation and rather thick, short, appressed, whitish setae. Posterior lobe slender, slightly convex with apex truncated in straight line.

Scutellum black, triangular, pointed, not raised, very minutely and closely punctured; surface covered with short setae.

Elytron reddish with suture, anterior and lateral margins black ( “ socia form”). Black sutural pattern sometimes broadened at about midline or along whole anterior half. Less frequently, black pattern extended to form a black transverse line connecting lateral margin to suture just behind midline, splitting reddish pattern into two separate subrounded spots, anterior one distinctly larger ( “ rubronotata form”). Elytral outline cylindrical, rather short, regularly convex, with sides almost parallel or slightly convergent toward apex. Lateral margins narrow, not visible from above. Scutellar area not raised. Humeral callus prominent, not punctured. Elytral surface matt, with fine punctures arranged in well-visible, almost regular rows. All elytral surface with sparse, short, appressed setae. Sometimes such pilosity almost missing. Epipleura narrow, with plane or slightly concave, slightly rugose and shortly setose surface.

Pygidium black, matt, covered by very fine punctures and rather thick, appressed, whitish setae.

Ventral surface black, matt, covered with thick, long, appressed, whitish setae, except scarcely setose, shiny posterior part of hypomera. Prosternal process wide, short and transverse, with sides raised at middle in small tooth-like process; posterior angles broadened and pointed; surface finely punctured, covered with thick appressed setae; posterior margin straight.

Legs completely black.Anterior and median tibiae with no sexual modifications. Anterior and median tarsomeres slightly swollen.

Fifth abdominal ventrite devoid of median depression along posterior margins. Posterior margin of fifth abdominal ventrite straight.

Median lobe of aedeagus ( Figs. 16d–f ) short, squat. Ventral surface strongly concave with no clues of median carina. Shaft terminated with blunt, short triangular apex. Setose depressions slender, shallow, scarcely delimited, extended along sides up to middle of shaft. Setigerous lamellae, small, elliptical, with single line of setae along distal edge.

Female. Habitus in Fig. 5e . BL = 3.1–3.3 mm, BW = 2.0– 2.1 mm, PL = 1.2–1.3 mm, PW = 1.9–2.0 mm. Interocular distance 19.4–21.2 % of BL.

Females differ in larger size, slenderer anterior and median tarsomeres, shorter outline and slightly larger interocular distance, shorter and slenderer antennae. The most common elytral colour pattern is “ rubronotata form” which is quite rare in males. Conversely, the most frequent male design ( “ socia form”) is decidedly rare in females.

Fifth abdominal ventrite in females with shallow pit with a flat, bald, slightly shiny, not punctured base.

Vasculum of spermatheca ( Figs. 24e–f ) is slender, hook-shaped, with proximal and distal lobes not swollen, approximately of same length. Distal lobe is mildly tapered towards a pointed and straight apex. Ampulla is lengthened, cylindrical. Duct insertion and sperm gland insertion fully separate, the latter sitting at proximal end of ampulla. Duct is fine, long, not coiled but forming a loose tangle at about mid length. Proximal section is thickened, rigid and curved.

Remarks. Variation in elytral colour pattern, which caused previous authors to describe and consider two different species, seems to be an interesting example of incomplete sexual dimorphism.

Figures

FIGURE 3. Mylassa obliquata. a–b: male, habitus in dorsal and lateral view (Curacautín, Araucanía, Chile); c: frontal view, male (Curacautín, Araucanía, Chile); d: frontal view, female (E of Lago Ranco, Chile); e–q: colour variations (e: LT of M. obliquata, male, “Chile”; f: HT of M. chachallaoi, Frutillar, Los Lagos, Chile; g: male, Santa Elisa, Los Ríos, Chile; h: male, Curacautín, Araucanía, Chile; k: PLT of M. obliquata, female, “Chili”, SDEI; m: male, Petrohué, Los Lagos, Chile; n: female, E of Lago Ranco, Los Ríos, Chile; p: female, W of La Unión E of El Mirador, Los Ríos, Chile; q: PLT of M. chachallaoi, male, Puerto Radal Isla Victoria, Neuquén, Argentina, IFML). Images not to scale.

FIGURE 4. Mylassa pectinicornis. a–c: male, habitus in dorsal (a–b) and lateral (c) view (Pucón, Araucanía, Chile (a); Parque Nacional Villarrica, Chile (b–c)); d: frontal view, male (Pucón, Araucanía, Chile); e: frontal view, female (Parque Nacional Villarrica, Araucanía, Chile); f–g: colour variations (f: female, Pehuenco Parque Nacional Nahuelbuta, Araucanía, Chile; g: female, Parque Nacional Villarrica, Araucanía, Chile). Images not to scale.

FIGURE 5. Mylassa rubronotata. a–c: female, habitus in dorsal (a), lateral (b) and frontal (c) view (LT of M. rubronotata, “Chili”); d–f: colour variations (d: female, PLT of M. rubronotata, “Chili”; e: female, Rio Maipo, Santiago, Chile; f: male, Rio Maipo, Santiago, Chile). Images not to scale.

FIGURE 12. Pronotum. a: Mylassa crassicollis (Petorca, Valparaíso, Chile); b: M. frigens (Trancas Chillán, Ñuble, Chile); c: M. obliquata (Curacautín, Araucanía, Chile); d: M. pectinicornis (Pucón Villarrica, Araucanía. Chile). Images not to scale.

FIGURE 13. Pronotum. a: Mylassa rubronotata (Curicó E. of Potrero Grande, Maule, Chile); b: M. monrosi (HT, Antillanca, Los Lagos, Chile); c: M. fuliginosa (PT, Cord. Nahuelbuta Pichinahuel, Chile); d: M. flavolimbata (PT, Embalse Bullileo, Ñuble, Chile). Images not to scale.

FIGURE 15. Median lobe of the aedeagus in ventral (left), dorsoapical (center) and lateral (right) views. a–c: Mylassa crassicollis (Cerro Robles saddle, Santiago, Chile); d–f: M. frigens (Currhué Parque Nacional Lanin, Neuquén, Argentina); g–i: M. obliquata (E of Lago Ranco, Los Ríos, Chile). All images in the figure courtesy of Michele Zilioli (MSNM).

FIGURE 16. Median lobe of the aedeagus in ventral (left), dorsoapical (center) and lateral (right) views. a–c: Mylassa pectinicornis (Ralco, Biobío, Chile); d–f: M. rubronotata (Curicó E of Potrero Grande, Maule, Chile); g–i: M. monrosi (PT, Parque Nacional Los Alerces, Chubut, Argentina). All images in the figure courtesy of Michele Zilioli (MSNM).

FIGURE 19. Median lobe of the aedeagus with everted endophallus. Mylassa crassicollis (Pichinahuel Cord. Nahuelbuta, Araucanía, Chile), in ventral (a) and lateral (b) views [scale bar = 0.6 mm]. M. frigens (Lonquimay, Araucanía, Chile) in dorsal (c) and lateral (d) views [scale bar = 1.0 mm]. sc1–sc4: sclerites of endophallus; sl: setigerous lamella. All images in the figure courtesy of Maurizio Bollino (Lecce).

FIGURE 20. Median lobe of the aedeagus with everted endophallus. Mylassa obliquata (W of La Unión, Los Ríos, Chile), in dorsal (a) and lateral (b) views [scale bar = 0.9 mm]. M. pectinicornis (Pucón, Villarrica, Araucanía, Chile) in dorsal (c) and lateral (d) views [scale bar = 1.1 mm]. sc3: sclerite of endophallus; sl: setigerous lamella. All images in the figure courtesy of Maurizio Bollino (Lecce).

FIGURE 24. Spermatheca. a–b: Mylassa obliquata [scale bar = 0.5 mm]; c–d: M. pectinicornis [scale bar = 0.4 mm]; e–f: M. rubronotata [scale bar = 0.4 mm].

FIGURE 26. Distribution maps. a: Mylassa crassicollis; b: M. frigens; c: M. obliquata; d: M. pectinicornis; e: M. rubronotata.