Lasioglossum (Dialictus) paxtoni Landaverde-González & Gardner & Moo-Valle & Quezada-Euán & Ayala & Husemann 2023, sp. nov.
Creators: name: Landaverde-González, Patricia
name: Gardner, Joel
name: Moo-Valle, Humberto
name: Quezada-Euán, José Javier G.
name: Ayala, Ricardo
name: Husemann, Martin
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Halictidae
Lasioglossum
Lasioglossum paxtoni

description: Lasioglossum (Dialictus) paxtoni Landaverde-González sp. nov.
urn:lsid:zoobank.org:act: 8AB32A78-9274-49AE-B9CA-3D2BF1A925BE
Figs 5C–D, 6B, 9–10, 28A, 29A, 30A
Diagnosis
Females of L. paxtoni sp. nov. can be recognised by having the vertex and mesoscutum with very short, sparse pubescence as if shaved (most noticeable in lateral view where most setae are separated by half or more their length); tegula enlarged (reaching posterior margin of mesoscutum in dorsal view; tegula width/ITS 0.21–0.22) and lateral margin with shallow, minute, and sparse punctures (i = 1–2d) no larger than mesoscutum punctures (sometimes inconspicuous and tegula nearly impunctate); mesoscutum shiny, finely and sparsely punctate (i = 1–3 pd), becoming slightly denser laterad of parapsidal lines (i = 1–2 pd), and with distinct red–brassy reflections medially; mesepisternum shiny, granular and finely, moderately densely punctate (i = 1–1.5 pd); metapostnotum with fine rugae extending onto propodeum dorsolateral slope; discs of T1–T2 with very fine, minute punctures, often hardly visible; and T2 and usually T3 apical impressed areas glabrous and impunctate. Males can be recognized by the same characters, except that the mesoscutum color is less red and more brassy, and the mesepisternum is more densely punctate (i <1 pd), the mesoscutum has sparse plumose setae 0.5–1 OD long (most setae separated by half their length or more in lateral view, especially in posterior half).
Differential diagnosis
Both sexes of L. paxtoni sp. nov. are most similar to L. yucatanense sp. nov., L. (D.) aureoviride sp. nov., specimens of the Lasioglossum stictaspis species complex, the Nearctic species L. perparvum, and some undescribed species related to L. perparvum which are not known to co-occur with L. paxtoni. See the differential diagnosis for L. yucatanense for characters separating these species. Lasioglossum (D.) aureoviride has the mesoscutum weakly tessellate and sparsely punctate between the parapsidal lines (i = 1–3 pd) and with dense erect setae ~1 OD long (all setae separated by less than half their length in lateral view); T2–T3 apical rims evenly covered with fine setae and/or punctures; mesoscutum with dense erect setae ~1 OD long and subappressed setae 0.25–0.5 OD long; mesepisternum imbricate and very densely punctate (i <0.5 pd).
Specimens of Lasioglossum stictaspis species complex have the mesepisternum imbricate and deeply, moderately densely punctate (i ≤ 1.5 pd) with distinct interspaces, T2–T3 apical rims evenly covered with fine setae and/or punctures. Females of L. perparvum have the scutum olive green with no red reflections, tarsi dark brown, scutum tessellate, mesepisternum tessellate with indistinct punctures, and
T2–T3 with extensive basolateral fine tomentum covering about half length of segment laterally and apical impressed areas minutely punctate with fine setae associated with punctation.
One undescribed species from western Veracruz labeled as L. sp. mex9 on BOLD is especially similar to L. paxtoni sp. nov., but lacks copper-red reflections on the mesoscutum and the tegula is more deeply and distinctly (but still sparsely) punctate. This species is apparently restricted to high elevations in the Sierra Madre Oriental mountains, in contrast to L. paxtoni which is restricted to the Yucatán Peninsula and northern Chiapas.
Etymology
The specific epithet is in dedication to Prof Robert Paxton, the PhD advisor of PLG and JQE.
Type material
Holotype MEXICO – Yucatán • ♀; Yaxnic; [20.79° N, 89.62° W]; 8 Apr. 1997; R.W. Brooks, H. Delphin, H. Contreras and U. Mao leg.; ex Momordica charantia; SEMC SM0106374.
Paratypes MEXICO – Campeche • 1 ♂; 10 mi N of Hopelchén; [19.89° N, 89.84° W]; 17 Apr. 1962; L. A. Stange leg.; UCDC. – Chiapas • 1 ♀; San Juan Cancuc, Tzajalchén; 16.9474° N, 92.3578° W; elev. 1020 m; 4 Feb. 2010; Philippe Sagot leg.; ECOAB.43220 • 1 ♂; same collection data as for preceding; ECOAB.43235 • 1 ♀; San Juan Cancuc, Tzuluwitz; 16.894° N, 92.4019° W; elev. 1270 m; 5 May 2009; Jorge Mérida, César López and T. López leg.; ECOAB.42654. – Quintana Roo • 2 ♂♂; Xcan; [20.87° N, 87.6° W]; 31 Jul. 1962; A. B. Amerson Jr. leg.; SEMC. – Yucatán • 1 ♂; Xmatkuil, 15 km S of Mérida; [20.86° N, 89.62° W]; 13 Feb. 1987; Charles D. Michener leg.; SEMC • 2 ♀♀; Mérida; [20.97° N, 89.59° W]; Nov. 1961; N.L.H. Krauss leg.; SEMC • 1 ♀; Mérida, 15 km S of University of Yucatán; [20.83° N, 89.62° W]; 7 Apr. 1997; R.W. Brooks leg.; ex Piscidia piscipula; SEMC SM0105915 • 1 ♂; Yaxnic; [20.79° N, 89.62° W]; 8 Apr. 1997; R.W. Brooks, H. Delphin, H. Contreras and U. Mao leg.; ex Momordica charantia; SEMC SM0106372 (photographed).
Other material examined
MEXICO – Yucatán • 1 ♀; Alfonso Caso; 20.084° N, 89.1609° W; 25 Oct. 2011; Quezada-Euán and Moo-Valle leg.; ZMH 842027 • 1 ♂; Yaxcopil; [20°4′4.10″ N, 88°54′23.80″ W]; 25 Oct. 2011; Quezada-Euán and Moo-Valle leg.; original label 38b; ZMH 81029 • 1 ♀; Santa María; [20°23′32.5″ N, 88°55′14.6″ W]; 26 Jul. 2011; Quezada-Euán and Moo-Valle leg.; original label 587e; ZMH 81040 • 1 ♀; Alfonso Caso; [20°05′02.5″ N, 89°09′39.3″ W]; 25 Oct. 2011; Quezada-Euán and Moo-Valle leg.; original label 81; ZMH 842025 • 1 ♀; same collection data as for preceding; original label 87; ZMH 842026 • 1 ♀; same collection data as for preceding; original label 91; ZMH 842027 1 ♀; Yaxcopil; [20°4′4.10″ N, 88°54′23.80″ W]; 1 Aug. 2011; Quezada-Euán and Moo-Valle leg.; original label 602c; ZMH 842029 • 1 ♀; same collection data as for preceding; original label 86; UADY.
Floral records
CUCURBITACEAE Juss.: Momordica L.: M.charantia L. • FABACEAE Juss.: Piscidia: P. piscipula (L.) Sarg. • SOLANACEAE Adans.: Capsicum L.: C. chinense Jacq.
DNA barcodes
Five sequences available (BOLD process IDs: LDSPS029-15 to LDSPS033-15). The attribution of these sequences to L. paxtoni sp. nov. is based on their genetic similarity to the undescribed L. sp. mex9, which is morphologically similar to the description of L. paxtoni (unfortunately the specimen originally designated as a holotype was destroyed), and the small number of available sequences (consistent with the low relative abundance of L. paxtoni). The sequences are variable and distinguished from those of other species (maximum intraspecific p-distance 0.82%; minimum interspecific p-distance (to L. yucatanense sp. nov.) 2.89%).
Description
Female (holotype)
MEASUREMENTS. Length 3.75 mm; head length 1.05 mm; head width 1.08 mm; fore wing length 2.43 mm. Five female paratypes measured: length 3.75–4.4 mm; head length 1.05–1.11 mm; head width 1.08– 1.17 mm; forewing length 2.43–3.21 mm.
COLOUR. Head and mesosoma metallic blue-green with red-brassy reflections dorsally; scape and pedicel dark brown; F1–F10 dark brown dorsally, orange-brown ventrally; tegula orange-brown; wing membrane subhyaline, venation and pterostigma dark brown; legs dark brown with tarsi lighter orangebrown; metasoma dark brown.
PUBESCENCE. Light yellow; head and mesosoma with moderately abundant setae (1–2 OD), very short and sparse on vertex, gena, and mesoscutum (<1 OD); lower paraocular area with sparse subappressed tomentum; propodeum with plumose long setae (2–2.5 OD) on lateral and posterior surfaces, in the latter sparser; T1 with sparse complete setose fan; T1–T6 evenly covered with very short, sparse, simple setae, except T1–T2 apical impressed areas glabrous, tarsal segments with plumose, light-yellow setae.
SURFACE SCULPTURE. Clypeus shiny and moderately densely punctate (i = 1–2 pd); supraclypeal area shiny and sparsely punctate (i = 1–3d); paraocular area shiny and densely punctate (i ≤ 1 pd); frons dull with very fine crowded punctures (i = 0 pd); ocellocular area shiny and moderately sparsely punctate (i = 1–2 pd); gena and postgena lineate; tegula lateral margin with a few shallow, minute, and sparse punctures (i = 1–2d), otherwise impunctate; mesoscutum shiny and sparsely punctate medially (i = 1–3 pd), becoming moderately dense laterad of parapsidal lines and posteromedially (i = 1–1.5 pd); mesoscutellum weakly tessellate and moderately sparsely punctate (i = 1–2 pd); axilla similar to mesoscutellum; metanotum very finely rugulose; mesepisternum granular, shiny and moderately fine and densely punctate (i = 1–1.5d); metepisternum very finely rugulose; metapostnotum reticulate with fine subparallel rugae reaching posterior margin; propodeum lateral and posterior surface finely reticulate; discs of metasomal terga weakly coriarious and very minutely, sparsely, obscurely punctate (i = 2–4 pd); apical impressed areas impunctate; T2 and usually T3 apical rims impunctate.
STRUCTURE. Head square (length/width ratio = 0.99–1.01; holotype:1.0); eyes weakly convergent below (UOD/LOD ratio = 1.29–1.31; holotype = 1.33); clypeus ½ below suborbital tangent; antennal sockets close (IAD/AOD = 0.53-0.65), frontal line ending 2.5 OD below median ocellus; gena wider than eye; inner metatibial spur pectinate with 2–3 teeth; tegula relatively large, reaching posterior margin of mesoscutum in dorsal view, with inner posterior margin straight, more bean-shaped; scutellum length 0.22; metapostnotum length 0.15, metapostnotum moderately elongate (MMR ratio = 1.47), weakly rounded posteriorly; propodeum with oblique carina, lateral carina nearly reaching margin of dorsal surface.
Male
MEASUREMENTS. Length 3.53–3.85 mm; head length 0.86–1.01 mm; head width 0.95–1.18 mm; fore wing length 2.02–2.58 mm.
COLOURATION. Head and mesosoma dark turquoise-green to olive green with brassy-gold reflections dorsally; antenna dark brown dorsally, orange-brown ventrally; wing membrane subhyaline, venation and pterostigma dark brown; legs dark brown with tarsi lighter orange-brown; metasoma dark brown.
PUBESCENCE. Light yellowish; head and mesosoma with moderately abundant setae (1–2 OD), very short and sparse on vertex and mesoscutum (<1 OD); lower paraocular area with dense subappressed tomentum; mesoscutum with sparse plumose setae 0.5–1 OD long (most setae separated by half their length or more in lateral view, especially in posterior half); propodeum with short plumose setae on lateral and posterior surfaces (0.5–1 OD); discs of metasomal terga covered with sparse, short, simple setae.
SURFACE SCULPTURE. Clypeus, supraclypeal area, and lower paraocular area shiny and densely punctate (i ≤ 1 pd), upper paraocular area and frons shiny with crowded punctures (i = 0 pd), ocellocular area shiny and densely punctate (i ≤ 1 pd); gena and postgena lineate; mesoscutum shiny and sparsely punctate (i = 1–3 pd), becoming slightly denser laterad of parapsidal lines (i = 1–2 pd); mesoscutellum shiny and moderately densely punctate (i = 1–2 pd); tegula sparsely punctate (i = 2–4 pd), more sparse medially (i> 1.5 dp), sometimes inconspicuous and tegula nearly impunctate; mesepisternum granular, shiny and densely punctate (i <1–1.5 pd); propodeum lateral surface finely reticulate, posterior surface shiny and moderately densely punctate (i = 1–2 pd); discs of T1–T3 shiny and moderately sparsely punctate (i = 1–3 pd) sometimes impuctate; apical impressed areas and discs of T4–T6 impunctate.
STRUCTURE. Head slightly long (length/width ratio = 1.01–1.04); eyes weakly convergent below (UOD/ LOD ratio = 1.29–1.62); clypeus ½ below suborbital tangent; antennal sockets slightly close (IAD/ AOD <1.42); frontal line ending 2.5 OD below median ocellus; gena narrower than eye; tegula relatively large, reaching posterior margin of mesoscutum in dorsal view, with inner posterior margin straight or concave; scutellum length 0.19; metapostnotum length 0.15, metapostnotum elongate (MMR ratio = 1.27), weakly rounded onto posterior surface; propodeum with lateral carina not reaching margin of dorsal surface; genitalia with penis valve small and delicate, retrorse lobe small, gonostylus of medium size and with a few short, simple setae near apex; S7 median process narrow; S8 median process wide.
Distribution
Only known from the Yucatán Peninsula and northern Chiapas.
Remarks
Rare and apparently geographically restricted to the Yucatán Peninsula. This species is a member of the L. gemmatum species complex and corresponds to mOTU 2 in Landaverde-González et al. (2017a).
description: Published as part of Landaverde-González, Patricia, Gardner, Joel, Moo-Valle, Humberto, Quezada-Euán, José Javier G., Ayala, Ricardo & Husemann, Martin, 2023, Seven new species of Lasioglossum (Dialictus) Robertson, 1902 (Hymenoptera: Halictidae: Halictini) from the Yucatán Peninsula, Mexico, pp. 1-65 in European Journal of Taxonomy 862 (1) on pages 19-24, DOI: 10.5852/ejt.2023.862.2079, http://zenodo.org/record/7767855