Chilicola (Pseudiscelis) nanula Packer

Packer, Laurence & Genaro, Julio A., 2007, Fifteen new species of Chilicola (Hymenoptera: Apoidea; Colletidae), Zootaxa 1468, pp. 1-55 : 18-22

Chilicola (Pseudiscelis) nanula Packer , n. sp.

( Figs.7A–O )

Diagnosis: This species is a member of the subgenus Pseudiscelis based upon the comparatively long pronotum ( Fig. 7F ) combined with the absence of a facial fovea ( Figs. 7B and D ) and also the hitherto unnoticed synapomorphy for the subgenus of a seven segmented maxillary palpus ( Fig. 7E ).

The small body size (head length less than one millimeter) and malar space with length and breadth subequal ( Fig. 7A ) are diagnostic for the new species within the subgenus Pseudiscelis except for two additional undescribed species, one of which is sometimes sympatric, the other from Bolivia. The antenna of the second small Argentinian species reaches the metanotum when curved back over the dorsum and is approximately 1.25X as long as the entire mesosoma , the pronotal lobe is entirely yellowish and the clypeus entirely yellow. In contrast, the antenna of C. nanula barely reaches the base of the scutellum and is less than 1.15X the length of the mesosoma , the pronotal lobe is entirely dark (sometimes edged with testaceous) and the clypeus is narrowly dark laterally, broadly so (broader than the maximum width of the scape) dorsally such that the pale marking on the clypeus extends only two thirds as far up the face (or less) as does the pale marking on the paraocular area. Females of the two species can be differentiated by the dark pronotal lobe and lower face of C. nanula , whereas the other species has at least the posterior half of the pronotal lobe orange with a yellowish posterior rim, a yellow marking laterad of the groove below the anterior tentorial pit and orange markings on the lower margin of the clypeus and on the malar area. Males of C. nanula can be differentiated from those of the Bolivian one by its shorter head, only 1.3X as long as wide, versus almost 1.5X as long as wide in the Bolivian species. S7 differs between the two species: in C. nanula the capitate setae at the apex of the posterolaterally oriented dorsal lobe do not reach the apex of the fine setae at the end of the posteriorly oriented ventral lobe, whereas in the Bolivian species the capitate setae are longer and reach the apex of the setae on the ventral lobe. It is not yet possible to differentiate the females of C. nanula and the Bolivian species.

Description. Male: body length 3.2mm, forewing length 2.3mm, head width 0.7mm.

Colouration: Black, legs and metasoma brown. Following parts yellow: mandible (apex testaceous), labrum, clypeus (except for band adjacent to epistomal suture, band broader dorsally), lower paraocular area to beneath antennal socket separated from socket by one socket diameter, ventral surface of scape and pedicel, apical one-third of forefemur, anterior and dorsal surfaces of foretibia and foretarsus, basal ring on mid- and hindtibia, mid- and hindtarsomeres (darkening somewhat towards pretarsus). Following parts yellow-orange: ventral surface of antennal flagellum and apical rings to mid and hind tibiae. Dorsal surface of flagellum orange-brown. Tegula amber. Wing veins pale brown. Apical impressed areas of metasomal terga amber.

Surface Sculpture: Body surface moderately dull due to microsculpture, shinier on scutellum, sides of thorax and metasomal terga. Labrum moderately densely punctate, i<d. Face below antennae with sparse punctures (i~2–3d); upper paraocular area and frons with larger, deeper, denser but irregular punctures (i=0.5–2d). Vertex behind ocelli transversely microstriate with few punctures. Genal area shallowly and irregularly punctate (i=1–5d) on weakly, longitudinally microstriate background. Pronotum irregularly punctate (i=0.5–2d), punctures larger than elsewhere. Mesoscutum distinctly punctate (i~d); scutellum and metanotum with slightly sparser punctures. Mesopleuron irregularly punctate, i=1–3d. Dorsal surface of propodeum rugose on disc with strong median longitudinal carina attaining posterior margin, lateral portion of dorsal surface minutely but deeply roughened, lateral surface of propodeum weakly rugulose, dorsolateral area strongly rugose. Metasomal terga somewhat shiny with shallow microsculpture; T1 punctures very shallow and sparse; remaining terga with minute sparse punctures; apical impressed areas with very weak microsculpture.

Pubescence: White, short, sparse and fine throughout (<0.5OD) with few longer hairs on gena (<1.5OD) not forming beard. No posterolateral hair patches on metasomal terga. No specialized areas on metasomal sterna, which are glabrous except for short, sparse, suberect hairs on posterior 0.33X and transverse subapical row of somewhat longer hairs (~0.5OD), somewhat longer on S5 (~1MOD).

Structure: Head: ( Figs. 7A and B ) Longer than broad 60:45. Labrum transverse, oval, length to breadth 7:11. Mandible length to basal depth 20:11. Clypeus elongate, length to breadth 20:13 ( Fig. 7B ), extending below lower ocular tangent for one-third of its length, with very weak longitudinal medial depression. Epistomal suture expanded from above anterior tentorial pit almost to apex, anterior tentorial pit adjacent to suture. Subantennal sutures slightly convex outwardly; supraclypeal area 2X as long as apical breadth, well defined above ending just below midpoint of antennal socket. Frontal line distinctly raised for more than lower one-third of distance between upper margin of antennal socket to median ocellus, otherwise indistinct. Frons lacking swellings or depressions. Facial fovea absent. Inner eye margins weakly emarginate, eyes strongly convergent below ( Fig. 7B ); UOD:LOD 27:13. OOC 1.3X diameter of lateral ocellus; OOC:IOC 13:25. In frontal view, vertex strongly convex between eye and lateral ocelli, flat between lateral ocelli, expanded above compound eye. Upper orbital tangent below ventral tangent of median ocellus by <MOD. Scape 3X as long as greatest breadth, equal in length to pedicel and first two flagellomeres combined; pedicel longer than broad 10:7; F1 longer than broad ( Fig. 7B ); F2 and F3 with length and breadth subequal; remaining flagellomeres with length and breadth subequal except F11 1.5X as long as broad; flagellum gradually increasing in breadth from base to apex; flagellomeres lacking unusual patterns of setation or structural modifications. Face not protuberant in profile. Vertex in profile with shallow transverse depression just in front of occipital margin, occipital margin strongly carinate. Malar space shorter than basal depth of mandible (10:8), malar suture distinct. Ratio of gena:eye 12:20, eye broadened below middle ( Fig. 7A and B ).

Mesosoma: Elongate , length to greatest depth 15:7. Pronotum elongate ( Fig. 7F ), collar 1.5X as long as LOL, rounded anterolaterally. Episternal groove well developed below scrobe; scrobal groove absent anterior to scrobe, weak and oriented posterodorsally behind. Propodeum longer than scutellum, ratio of length of scutellum: metanotum: propodeum 22:11:29. Propodeal sulcus shallow anteriorly, formed of well defined transverse pits on posterior surface of propodeum. Hind femur not expanded, length 3X greatest depth, ventral surface convex ( Fig. 7G ). Hind tibia very narrow in basal half, somewhat expanded towards apex, almost 5X as long as apical depth ( Fig. 7G ); hind tibial spurs unmodified. Hind basitarsus more than 6X as long as greatest depth, subparallel. Hind tibial claws bifurcate. Basal vein weakly curved; ratio of length of stigma to marginal cell beyond stigma 20:28; stigma in marginal cell strongly convex; distal stigmal perpendicular near middle of second submarginal cell; 1st submarginal cross-vein interstitial or slightly apical to first recurrent vein.

Metasoma: T1 longer than broad 35:28. Apical impressed portions of terga 0.25X as long as terga, longer on T3 0.33X length of tergum. Sterna unmodified; S2 gradulus with long posteriorly directed lateral portion; graduli lacking on S3–S6;

Terminalia . S7 ( Fig. 7H ) with two lateral lobes, apical lobe posteriorly directed, narrow, acutely pointed, membranous and bearing several long setae; basal lobe elongate, cylindrical, somewhat posteriorly directed, slightly broader at base, apex with cluster of ventrally directed, thick peg-like capitate setae. S8 ( Fig. 7I ) with apical process long, parallel-sided, truncate at apex. Gonobase with short, broadly concave ventral process. Volsella U-shaped with apex of cuspis somewhat less than right angle, lateral surface concave subapically. Gonostylus narrow and elongate, poorly differentiated from gonocoxite. Penis valve with two membranous lobes directed dorsolaterally ( Fig. 7J ).

Female: body length 3.2mm, wing length 2.1mm, head width 0.7mm.

Colouration: Black-brown with malar space, apex of clypeus and lower paraocular area dark testaceous. Rest as in male but with pale markings on legs somewhat darker and more restricted in size.

Surface Sculpture: As for male except somewhat less dull throughout due to slightly weaker microsculpture; punctures smaller, shallower and somewhat sparser throughout.

Pubescence: Sparse and short. Scopal hairs on hind tibia 1.5MOD, scopa on S2 forming corbicula of long hairs <3.5 MOD, with short branches on anterior surface.

Structure: Maxillary palpus 7-segmented ( Fig. 7E ) with 2nd segment shortest, segments 5–7 of equal length, 4th segment longest, entire palpus 0.625X as long as prementum. Mouthparts elongate, prementum almost 6X as long as greatest breadth, fovea almost entirely covering ventral surface, lateral margins strongly carinate. Lacinia an elongate, narrow, hairless strap, more than 10X as long as greatest width. Lorum barely 2X as long as wide. Rest as for male except for normal sexual differences and as follows: Lower paraocular area broader, somewhat swollen laterally. Dorsal surface of propodeum subequal in length to scutellum, ratio of scutellum:metanotum:propodeum 26:12:30. Propodeal sulcus indistinct. Apical lunule of S5 semicircular.

Sting apparatus: Hemitergite 7 elongate ( Fig. 7K ), 2.3X as long as broad; medial portion of marginal ridge strongly concave; base of lateral process broad; spiracle approximately equidistant from lateral, medial and posterior margins of lamina spiracularis, posteriorly oriented; posterior margin of lamina spiracularis concave. Hemitergite 8 ( Fig. 7L ) with apodeme much broader than plate, anterior margin bent anteriorly at lateral extremity, anterior ridge slightly concave, margin between apodeme and plate sinuate. First valvifer ( Fig. 7M ) with ventral arm much longer than dorsal one. Gonostylus short, bearing short setae ( Fig. 7M ). Sting shaft long and narrow, ventral margin straight ( Fig. 7N ). Furcula with ventral arms broad; dorsal arm as long as ventral arms, elongate oval in lateral view ( Fig. 7O ).

Material studied. Holotype male and allotype female: ARGENTINA, La Rioja, Departamento Rosaro V., Penaloza, Sierra de Arganaraz, El Rocillo, 31o2066 S, 66 o7126 W, 2370 ft., 22.x.1997, M.E. Irwin, F.D. Parker and S. Roig; paratypes as follows: same data as holotype and allotype, seven males, three females; same locality and date but malaise trap, three male, four females; same data but pan trap, six males; same locality and collectors but 11.x.1997, two males; same data except 1km. W. of El Rocillo, 31o2071 S, 66 o7140 W, 2350 ft., 11–22.x.1997, M.E. Irwin, F.D. Parker and S. Roig, three males, eight females; same data but “E. base”, 31o2066 S, 66 o7126 W, 2370 ft., 11.x.1997, two females; La Rioja, Departamento General Lavalle, Piedra Pintada, 29o4261 S, 67o8134 W, malaise trap, M.E. Irwin, F.D. Parker and S. Roig, one female; La Rioja, Departamento Chilecito, 5km E. of Piedra Pintada, 29 o3598 S, 67 o7857 W, 2600ft, 12–15.x.1997, M.E. Irwin, F.D. Parker and S. Roig, one female; Catamarca, Andalgala 25.x.1972, G.E. Bohart, thirteen males, five females, all females and eight of the males collected from flowers of Prosopis alba (Fabaceae) , same data but 4.xi.1972, two males and three females, all from P. a l b a; Catamarca, 35km W. of Andalgala, 24.x.1972, G.E. Bohart, one female; Catamarca, 15km SE of Andalgala, 25.x.1972, G.E. Bohart, fifteen males, all but one from Acacia furcatispina (Mimosaceae) ; Catamarca, 15km S. of Colpes, 27.x.1972, G.E. Bohart, three males, ex P. a l b a; Catamarca, Andalgala desert scrub site, J.L. Neff, three females, same data thirty-three females; Catamarca, Andalgala, 11.ii.1972, ex Larrea cunifolia ( Zygophyllaceae )), W.D. Duckworth; Mendoza, Departamento Levalle, 20km N. of Parque Telteca, 32o2916 S, 67o3878 W, 23.x.1997, M.E. Irwin, F.D. Parker and S. Roig, one female. The Irwin et al., material except the holotype and allotype and Bohart's material, are housed at Logan except for 3 males and three females at PYU; one male and one female at each of AMNH and SEM, holotype and allotype and two paratypes of each sex at MACN; Duckworth’s specimen is at the USNM, Neff’s material is at CTMI.

Etymology. The specific epithet refers to the small size of this species.

Comments. Historically, the subgenus Pseudiscelis has been defined on the basis of the deep and elongate epistomal groove beneath the anterior tentorial pit, extension of the vertex above the eyes ( Figs. 7A–D ), elongate pronotum ( Fig. 7F ), absence of facial fovea and elongate malar area. All of these features except the last two are shared with the subgenus Prosopoides. The elongate malar area can no longer be considered as a characteristic of the subgenus, however, as there are numerous undescribed species some of which, such as C. nanula have a comparatively short malar space. The new species and all specimens referable to this subgenus, share the previously undetected feature of a 7-segmented maxillary palpus ( Fig. 7E ), which is found in no other groups of Chilicola .

This comparatively widespread species greatly expands our current understanding of the subgenus Pseudiscelis. Chilicola nanula stands at the opposite morphological extreme from the only other currently described species within the subgenus, C. rostrata (Friese) , which has a greatly enlarged malar space. There is an unknown number of additional species in the subgenus as now understood, all from Argentina with the exception of one species from Bolivia commented upon above. With the exception of one large species from Salta Province (mentioned as being undescribed in Michener 2000), they generally are intermediate in both size and length of the malar space between C. rostrata and C. nanula .

Some specimens of this species bear labels stating Pseudiscelis nana , which is a Moure manuscript name.

Figures

FIGURES 7 A – O. Chilicola nanula Packer, n. sp. Head of male: A. lateral view, B. frontal view. Head of female: C. lateral view, D. frontal view. E. maxillary palpus of female. Male: F. pronotum. G. hind leg. H. S 7. I. S 8. J. genital capsule. Dorsal views are at the left. K – O. Sting apparatus of female: K. hemitergite 7, L. hemitergite 8, M. First and second valvifer with gonostylus, N. sting shaft. O. furcula. Stippling in A and B indicates pale colouration, in J and M it indicates membranous areas.