Research Article |
Corresponding author: Quiyari Santiago-Jiménez ( quiyari@hotmail.com ) Academic editor: Jan Klimaszewski
© 2016 Quiyari Santiago-Jiménez, Rosny Santiago-Navarro.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Santiago-Jiménez QJ, Santiago-Navarro R (2016) A new genus and species of Placusini from a high mountain in Mexico. ZooKeys 640: 45-57. https://doi.org/10.3897/zookeys.640.10911
|
A new genus and species are described from the Cofre de Perote volcano, in the state of Veracruz, Mexico. Although the new genus is very similar to Placusa, it presents tergite VIII completely modified to form a horn, in both females and males, in addition to other differences in mouthparts. A map and illustrations are provided, as well as an identification key to the genera of Placusini. No morphological characters are apparent to separate Kirtusa Pace from Euvira Sharp in our genus key. The specimens of the new genus were collected using Lindgren and cross traps baited with a mix of semiochemicals: ipsenol, ipsdienol and lanierone.
Aleocharinae , Nearctic, Pinus forest, semiochemicals
The tribe Placusini currently includes four genera: Euvira Sharp is known from North America to Argentina, including the Antilles (
Here, a new genus of Placusini is proposed based on specimens collected on the Cofre de Perote volcano, Veracruz, Mexico. The new genus is very similar to Placusa, according to the Placusa diagnosis proposed by
From March to May in 2015, 28 specimens of Placusini were collected in the Cofre de Perote volcano, specifically in the locality Agua de los Pescados, Veracruz state, Mexico. The specimens were collected using handmade interception traps, baited with a mix of semiochemicals: ipsenol, ipsdienol and lanierone. Specimens were preserved in ethanol 70%, and later observed and identified using a Stemi DV4 stereoscopic microscope. For the illustrations, photographs were taken using an image processing system (VELAB microscope model VE-633 with Digital LCD model DMS-153). Permanent microscope slides were prepared using the techniques described by
Body shape fusiform, broad and strongly flattened; head transverse, with a suture between antennal insertions; sensillae on apical margin of epipharynx arranged in a pattern of anterior or a-sensilla, and lateral or ε-sensilla; prementun with medial pseudopore field present, with at least a few pseudopores in an irregular rectangular array, but pseudopores are extended to the lateral pseudopore field; mandibles with a large velvety patch completely occupying the base, composed of nine to eleven transverse rows of large teeth that are reduced in size to the base; labium with short rounded ligula, entire, and not divided; pronotum transverse, approximately 1.5 times wider than long, wider on medial third; mesocoxal cavities not separated by meso- and metaventrite processes; mesoventrite process short with apex acuminate; metaventral process medium-sized, marginate and with apex subobtuse; isthmus not present; tergite VII with lateral margin modified to form a structure-like wall on each side, which apparently provides support between tergite and sternite (only visible because of transparency on slides), and with an apical sclerotized plate attached internally (only visible because of transparency on slides) to receive tergite VIII; tergite VIII modified to form a horn (Figs
Body length 2.5–3.0 mm. Body shape fusiform, broad and strongly flattened; pronotum transverse. Tergite VIII modified to form a horn (Figs
Head. Transverse, with a suture between antennal insertions; surface with coarse punctures densely distributed. Antennomeres 4–10 transverse (Fig.
Placukorna ipsa Santiago-Jiménez, gen. n. and sp. n. male (8, 12, 14) and female (9, 13). 3 antenna 4 head 5 epipharynx 6 ligula, prementum, and labial palpi 7 pronotum 8 sternite VIII 9 sternite VIII 10 sternite VII tergite VIII 12 median lobe, lateral view 13 spermatheca 14 paramere, lateral view. Scale bars: 3–4, 7–11 = 0.2 mm; 5–6, 12–14, = 0.1 mm.
Mouthparts. Labrum: with 7 setae on each side of the midline; most of the setae on anterior half; with 17–19 sensory pores on each side of midline; sensillae on apical margin of epipharynx, arranged in a pattern of anterior or a-sensilla, and lateral or ε-sensilla (Fig.
Thorax. Pronotum transverse (Fig.
Abdomen. Abdomen fusiform (Fig.
The new genus is very close to Placusa; however, it can be distinguished easily by tergite VIII, which is modified completely to form a horn, and the sclerotized lateral internal wall of tergite VII, that apparently supports tergite VIII. Tergite VII has a sclerotized internal plate in the posterior margin that may also support tergite VIII. Moreover, there are some differences in the median lobe of Placusa (crista apicalis shorter) and Placukorna (crista apicalis longer; Fig.
Placukorna ipsa Santiago-Jiménez sp. n.
The genus name is a combination of “Placusa” and “korna”, from the Greek “Πλαξ” (meaning surface plane) and “κόρνα” (meaning horn), respectively.
Neuter.
Specimens were found in Lindgren and cross traps baited with ipsenol, ipsdienol and lanierone in a mixed pine forest. The forest is composed of Pinus pseudostrobus, P. montezumae and P. patula, located around 3090 m a.s.l.
The single described species, Placukorna ipsa, is known only from the Cofre de Perote volcano, in the central region of Veracruz state, in Mexico. Apparently, the genus is distributed in montane areas.
1 | Head transverse; without neck (Fig. |
2 |
– | Head quadrate to slightly transverse or transversally sub-orbicular; with neck (fig. 9.155 in |
3 |
2 | Male tergite VIII with a variable number of small to large spine–dents in the apex (figs 33–49 in |
Placusa Erichson, 1837 |
– | Male and female tergite VIII modified to form a curved horn (Figs |
Placukorna gen. n. |
3 | Head transversally sub-orbicular; pronotum with distinct anterior angles, posterior angles indistinct, with a long transverse sulcus; abdomen strongly narrowed from base to apex (fig. 1 in |
Speiraphallusa Pace, 2013 |
– | Head quadrate; pronotum with anterior angles broadly rounded, posterior angles distinct, without a long transverse sulcus; abdomen more or less parallel–sided to slightly widened (fig. 2 in |
Euvira Sharp, 1883 and Kirtusa Pace, 2008 |
México: Veracruz, Perote, Ejido Agua de los Pescados, 3090 m a.s.l., 19°31'30"N, 97°07'00"W, mixed pine forest, Lindgren trap # 14, 08–15.V.2015, P. Domínguez, C. Ruíz and R. Santiago.
Holotype, male, pinned. Original label: “México: Veracruz, Perote, Agua de los Pescados. B. Pino mixto, 19°31'30"N, 97°07'00"W, 3086 m, tr. Lindgren #14, 08.V–15.V.2015, P. Domínguez, C. Ruíz, R. Santiago”/ “MUZ-UV-COL-00003446”/ HOLOTYPE Placukorna ipsa Santiago-Jiménez, 2016” [red label].
Paratypes, same data as holotype except for: tr. de cruz # 6 (1 specimen ♂); same data except for: tr. de cruz # 8 (1 specimen ♀); same data except for: tr. de cruz # 7, 20.III–27.III.2015 (1 specimen on slide ♂); same data except for: tr. Lindgren # 11, 27.III–03.IV.2015 (6 specimens: 2 ♀ on slide; 2 specimens ♂ and 2 specimens ♀); same data except for: tr. Lindgren # 13 (1 specimen ♂); same data except for: tr. Lindgren # 14 (2 specimens: 1 specimen ♀ and 1 specimen ♂); same data except for: tr. de cruz # 6 (2 specimens ♂); same data except for: tr. de cruz # 7 (2 specimens ♀); same data except for: tr. de cruz # 9 (1 specimen ♂); same data except for: tr. Lindgren # 14, 10.IV–17.IV.2015 (1 specimen ♂); same data except for: tr. de cruz # 8, 17.IV–24.IV.2015 (2 specimens: 1 specimen ♂ and 1 specimen ♀); same data except for: tr. Lindgren # 13 (1 specimen ♀); same data except for: tr. de cruz # 7, 24.IV–01.V.2015 (1 specimen ♂); same data except for: tr. Lindgren # 12 (1 specimen ♀); same data except for: tr. Lindgren # 14 (1 specimen ♂); same data except for: tr. de cruz # 9, 01.V–08.V.2015 (2 specimens ♀); same data except for: tr. Lindgren # 12, 15.V–22.V.2015 (1 specimen ♂). All specimens deposited in MUZ-UV under numbers MUZ-UV-COL-00003447 to 00003473 [yellow label].
Although for the moment it is the only one known species to the genus, it is distinguished by the following combination of characters: body length 2.5–3.0 mm; head and pronotum dark brown and abdomen black; apical half or apical third of sternites III-VI reddish brown; elytra dark brown to black; coxae dark brown to black; metatrochanter and metafemur dark brown or yellowish brown, remaining legs yellowish brown; antennomeres 1–11 dark brown; surface of tergites and sternites III–VII with reticulate microsculpture, less evident on tergites III–IV; tergites III–VII with basal impression, III–V almost straight, VI posteriorly slightly curved, VII posteriorly evidently curved; tergite VI with a protuberance on each side of midline; spermatheca with small and approximately spherical capsule, median portion of spermathecal stem (duct) narrowly U–shaped, and posterior portion also U–shaped, with accessory gland; median lobe with moderately large bulbus, tubus almost straight, internal sac of median lobe with evident spinules, apex blunt in lateral view, with short compressor plate (less than half of median lobe), basal ridge convex and pointed; flagellum short, without coils in bulbus; process of crista apicalis long, almost straight and parallel to median lobe, rounded at the apex.
Body length 2.5–3.0 mm. Head and pronotum dark brown and abdomen black; apical half or apical third of sternites III-VI reddish brown; elytra dark brown to black; coxae dark brown to black; metatrochanter and metafemur dark brown or yellowish brown, remaining legs yellowish brown. The apical edge of tergite III can be reddish.
Head. Dorsal surface without impression, protuberance or carina on disc (Fig.
Mouthparts. As described for the genus.
Thorax. As described for the genus.
Abdomen. As described for the genus. Other conspicuous characters are: surface of tergites and sternites III–VII with reticulate microsculpture, less evident on tergites III–IV; tergites III–VII with basal impression, III–V almost straight, VI posteriorly slightly curved, VII posteriorly evidently curved, and tergite VI with a protuberance on each side of midline.
Secondary sexual structures. There are differences between the sexes in the shape of sternite VIII and the number of macrosetae on it (Figs
Female. Spermatheca with small and approximately spherical capsule, median portion of spermathecal stem (duct) narrowly U–shaped, and posterior portion also U–shaped, with accessory gland (Fig.
Aedeagus. Median lobe with moderately large bulbus, tubus almost straight, internal sac of median lobe with evident spinules, apex blunt in lateral view, with short compressor plate (less than half of median lobe), basal ridge convex and pointed; flagellum short, without coils in bulbus (Fig.
Placukorna ipsa is the only described species in the genus. The characters that could be useful at the species level are the shape of the aedeagus, spermatheca, and impressions and protuberances on the abdomen as described above.
Some characters that vary among the specimens collected are: protuberances on each side of midline of tergite VI are inconspicuous to prominent, one specimen had a raised midline from tergite III–VI, and the horn of tergite VIII is as long as tergite VII or tergites VI–VII together.
As the specimens were found associated with Scolytinae of the genera Ips DeGeer and Pseudips Cognato, the name makes reference to Ips from Greek “ἴψ” (meaning sort of worm), with Greek ending “a”.
Neuter.
Specimens of Placukorna are possibly living in galleries of Ips and Pseudips associated with different Pinus species of the mixed pine forest (Pinus pseudostrobus predominating) where they were collected. Specimens were collected using traps baited with a mix of semiochemicals (ipsenol, ipsdienol and lanierone), in which more than 180 specimens of Ips (94) and Pseudips (91) were also collected. The semiochemicals are commonly used in those traps to capture bark beetles (Scolytine), therefore, an association of specimens of Placukorna with Ips and Pseudips is plausible.
Placukorna ipsa sp. n. is known from the type locality in the central region of Veracruz, Mexico. Twenty-eight specimens of Placukorna ipsa sp. n. were captured by handmade intercept traps for bark beetles primed with the semiochemicals mentioned above, in mixed pine forest. The locality Agua de los Pescados is 3090 m a.s.l. on the northeast face of the Cofre de Perote, Veracruz, Mexico (Fig.
Tribe Placusini as proposed by
The new genus proposed here matched most of the synapomorphies of Placusini proposed by
The authors are grateful to their colleagues at the Facultad de Biología, Universidad Veracruzana and the Instituto de Ecología, A.C. for their support, particularly M. Morales, R. Ortega and R. Novelo for the use of the microscopes. We also thank A. Newton for sharing information from his database, C. Ruíz for the biological material provided, and P. Domínguez and R. Sánchez who provided the junior author with support in the field. We thank B. Delfosse for her careful correction of the English. We are also grateful to the two anonymous reviewers, who contributed to improve the manuscript with their valuable comments.