Loxopus Townes, 1970

Santos, Bernardo F. & Aguiar, Alexandre P., 2014, Review of Loxopus Townes (Hymenoptera, Ichneumonidae, Cryptinae), with descriptions of six new species, Journal of Natural History 49 (31), pp. 1905-1935 : 1906-1916

Loxopus Townes, 1970

( Figures 1–8 )

Loxopus Townes, 1970 , 238, 255–256, 470. Description, figure, keyed. Type species: Loxopus australis Townes , by monotypy and original designation.

Diagnosis

Apical margin of clypeus laterally projecting as delicate to distinct triangular lobes ( Figure 2A,B ); mesosoma matt and densely covered with short pilosity; epomia short and delicate; lateral lobe of t4 much longer (at least 1.5×) than mesal lobe ( Figure 2D ); posterior transverse carina of propodeum forming weak but distinct sublateral crests; fore wing cell 1 + 2Rs (areolet) small, open, vein 3r-m absent; hind wing vein M + Cu subapically strongly arched; vein 2-1A almost always absent or vestigial ( Figure 2C ).

Female

Fore wing 3.38–6.45 mm long. Head. Mandible of moderate length, MLW 1.33–2.02, its apex distinctly narrower than base, MWW 0.47–0.59, dorsal tooth slightly longer and more robust than ventral one. Malar space from narrow to wide, MSM 0.47– 0.65. Clypeus moderately wide, CWH 1.58–1.81, trapezoidal, CWW 1.42–2.09; in profile, distinctly convex; apical margin convex, without median teeth, laterally projected sublaterally into delicate triangular lobes (Figure 3B); clypeal fovea large, rounded, connected to compound eye by delicate sulcus. Antenna with 20–27 flagellomeres; just beyond middle with a distinct, wide white band; subapical flagellomeres slightly thicker than basal ones, never flattened. Supra-antennal area near ocelli slightly convex, ventrally concave, densely punctulate; medially with delicate median longitudinal line. Occipital carina sharp, complete, meeting hypostomal carina above base of mandible.

Thorax. Generally matt and densely covered with dense and short pilosity. Dorsal margin of pronotum regular, not swollen; epomia short and delicate, divergent from pronotal collar. Mesoscutum subcircular, finely punctate; notaulus weakly impressed, in dorsal view distinct approximately on anterior 0.4 of mesoscutum; mesoscutum surface over notaulus with weak transverse wrinkles. Epicnemial carina restricted to ventral 0.5–0.8 of mesopleuron; sternaulus complete, weakly sinuous, striate, moderately impressed, weaker at posterior 0.35; median portion of posterior transverse carina of the mesothoracic venter short, straight. Hind margin of metanotum with small tooth-like projection; transverse furrow at base of propodeum narrow and moderately deep, with faint to distinct transverse striae. Pleural carina absent, or sometimes vestigial, often apparently present because of sculpture

Figure 3. (A) L. australis ; (B) L. dodecius ; (C) L. duckei ; (D) L. exius .

patterns of propodeum and metapleuron; juxtacoxal carina absent. Foretibia of female regular, not swollen; all t4 bilobed, lateral lobe at least 1.5 × as long as mesal lobe ( Figure 2D ).

Propodeum. Moderately short, 1.11–1.36 × as long as wide, matt, uniformly punctate, moderately pilose, pilosity denser laterally. Anterior margin medially straight or slightly concave. Spiracle elliptic, SWL 1.33–1.64, Anterior transverse carina complete, sharp, medially slightly to distinctly curved forward; distance from anterior transverse carina to anterior margin as long as that to posterior transverse carina. Posterior transverse carina usually complete, its median portion arched forward and usually weaker or sometimes obsolescent, sublaterally forming distinct but weak crests or flanges.

Figure 4. (A) L. ichilus ; (B) L. multicolor ; (C) L. tenuis ; (D) L. venezuelanus .

Wings ( Figure 2C ). Hyaline, fore wing length 4.20–5.20 mm, usually with brownish spot covering apical part of cells 2 + 3M (Townes’ second discoidal) and 1 + 2R (Townes’ discocubital). Fore wing vein 1-Rs + M with bulla placed basally; ramellus absent; crossvein 1cu-a forming distinct obtuse angle with M + Cu, arising basad or opposite of base of 1M + Rs; crossvein 2cu-a nearly as long as vein 2-Cu; vein 4-Rs approximately straight; cell 1 + 2Rs (areolet) small, APH 0.47–0.68, pentagonal, approximately as wide as high, AWH 0.94–1.13, open (3r-m not differentiated); veins 3-M and 4-M nebulous or spectral, 4-M distinctly longer than 4-Rs. Hind wing vein M + Cu subapically strongly convex; vein 1-Cu slightly to distinctly longer than crossvein 1cu-a, HW1C 1.18–2.00; crossvein 1r-m with bulla on posterior portion; vein 2-1A usually absent or vestigial, in one species sometimes distinct and reaching as much as 0.7 of distance to posterior margin.

Metasoma. T1 of moderate length, 0.35–0.40 × as long as combined length of T2–8, slender, T1LW 2.00–2.40, moderately triangular, T1WW 2.04–2.67, matt, with distinct basolateral tooth; spiracle on apical 0.4, not prominent; dorsolateral carina complete but usually delicate; median dorsal carina absent, ventrolateral carina distinct. Thyridium subcircular. T7–8 about as long as T5–6. OST 0.57–0.75; ovipositor thick, stout, slightly downcurved or approximately straight; basal half almost cylindrical, apical half laterally weakly compressed, progressively tapered; dorsal valve with nodus absent or very weak; ventral valve tip with distinct, though sometimes weak, teeth.

Males

Generally similar to the respective females. Morphological secondary sexual differences are usually more or less uniform within Cryptini, as noted by Santos and Aguiar (2013), and apply to the males of Loxopus as follows. General body size usually smaller than respective females. Antenna with 24–26 flagellomeres (body-size related), each flagellomere usually shorter and wider than in females; white band of flagellum starting more apically and usually covering more articles than in females of the same species. Transverse furrow usually slightly longer than in female. Propodeum smaller, less strongly convex, sublateral crests usually less distinct than in female ( Figure 7F ). Spiracle of propodeum usually circular or weakly elongate, SWL 1.00–1.50. Brownish spot on fore wing absent. First metasomal segment more slender, with T1LW around 2.6 (2.10–3.11), and less widened apically, with T1WW around 1.6 (1.41–1.79). T2–7 much more slender than in females.

Comments

All species of Loxopus are very similar in sculpturing, biometric ratios and colour pattern, usually being recognized by slight but distinctive features, particularly in the colour pattern. All of them agree well with the original definition of the genus. The unequal lobes of t4, hind wing vein 2-1A indistinct and the triangular projections at the margin of the clypeus suffice to distinguish Loxopus from all other Neotropical genera of Cryptinae. The projections on the clypeal margin, though, are usually quite inconspicuous and need to be examined under high magnification and proper lighting. The taxa described herein should run properly in the key provided by Townes (1970) for the world genera of Goryphina , except for the specimens of L. duckei sp. nov. that have a developed vein 2-1A (‘brachiella’ of Townes). In the ninth couplet of the key, the character ‘brachiella absent, or present and short, not reaching more than half the distance to wing margin’ could lead the user to the Afrotropical genus Bozakites Seyrig , though that is not the only character of the couplet. The available description and illustrations of Bozakites , however, should suffice to distinguish any species of Loxopus from it.

Sampling and biodiversity

The vast majority of the specimens examined in this work were collected with Moericke (yellow pan) traps, mostly as part of an extensive program of field trips that also used several Malaise traps, in the same sites and during the same period. This is in agreement with the findings by Aguiar and Santos (2010), suggesting that Moericke traps outperform Malaise traps in collecting many cryptine taxa, including Loxopus . The strong sex bias towards females observed herein is also in agreement with the results yielded by Moericke traps in Aguiar and Santos (2010). The collection of 41 specimens of L. australis in two days in Anchieta, Brazil, with a total effort of 720 trap-days (unpublished data) is particularly remarkable. This sampling success (one specimen for every 17.6 trap-days) contrasts with the few specimens reported in the literature so far, and may support the idea that Loxopus is a rather abundant group.

Biology

Unknown.

Distribution

Mexico, Costa Rica, Trinidad, Venezuela, Ecuador, Brazil (AM, PA, PI, MT, MG, ES, RJ, SP, PR, SC) and Bolivia ( Figure 8).

Key to the females of species of Loxopus

The following key can be tentatively used to determine males, but as male specimens are unknown for half of the species, its efficiency cannot be thoroughly assessed.

1 T3 mostly ferruginous or dark brown, sometimes with whitish lateral marks .......................................................................................................... 2

– T3 mostly white, sometimes with anterior brown or blackish semicircular mark ........................................................................................................... 4

2(1) T4 mostly white; postscutellum ferruginous (Figure 3B); antenna with 26–27 flagellomeres; fore wing length 5.1–6.4 mm ............. Loxopus dodecius sp. nov.

– T4 entirely ferruginous or almost so; postscutellum whitish; antenna with 23–25 flagellomeres; fore wing length 3.8–5.3 mm ................................................... 3

3(2) Mesoscutum entirely ferruginous (Figure 3A); anterior margin of mesopleuron ferruginous ( Figures 1 , 7D ); T2–3 usually with lateral whitish marks ( Figures 1 , 3A) ........................................ Loxopus australis Townes

– Mesoscutum black with central whitish mark; anterior margin of mesopleuron blackish; T2–3 entirely ferruginous ................................................................... .................................................. Loxopus unicolor Kasparyan et Ruíz-Cancino

4(1) Orbital band complete, gena light yellow or whitish along posterior margin of eye .................................................................................................................. 5

– Orbital band widely interrupted, gena mostly blackish or brown along posterior margin of eye ................................................................................................. 6

5(4) Posterior transverse carina of propodeum represented only by distinct, conical crests, elsewhere indistinct; T1 black with posterior whitish stripe; S4–6 whitish; all coxae with blackish marks, hind trochanter and femur laterally marked with black (Figure 4B) .................. Loxopus multicolor Kasparyan et Ruíz-Cancino

– Posterior transverse carina of propodeum complete, medially arched forwards, sublaterally forming distinct but delicate crests; T1 ferruginous with posterior whitish stripe (Figure 4D); S4–6 brown; all coxae and hind trochanters and femur without blackish marks ........................... Loxopus venezuelanus sp. nov.

6(5) Mesopleuron ventrally with distinct whitish mark; mesosternum with blackish marks ( Figure 7G ); T4–6 ferruginous (Figure 3D); dorsal margin of pronotum with whitish stripe ......................................................... Loxopus exius sp. nov.

– Mesopleuron and mesosternum entirely ferruginous, without whitish or blackish marks; T4–6 dark brown or blackish; dorsal margin of pronotum without whitish stripe .................................................................................................. 7

7(6) Ovipositor with weak nodus ( Figure 6C ); supra-clypeal area whitish, without dark marks; T1 mostly ferruginous, without blackish portions (Figure 4C) ..... ...................................................................................... Loxopus tenuis sp. nov.

– Ovipositor without a distinct nodus; supra-clypeal area with brownish or blackish marks; T1 at least partially blackish ................................................ 8

8(7) Fore wing with distinct brownish mark covering apical part of cells 2 + 3M and 1 + 2R; subalar ridge moderately wide, elliptic, light yellow ( Figure 7E ); T4–6 without lateral whitish marks (Figure 4A); hind wing vein 2-1A absent .......... ..................................................................................... Loxopus ichilus sp. nov.

– Fore wing without distinct brownish mark; subalar ridge very narrow, dashlike, ferruginous or whitish ( Figure 7C ); T4–6 with lateral whitish marks; hind wing vein 2-1A sometimes present .............................. Loxopus duckei sp. nov.

Figures

Figure 1. Loxopus australis, habitus.

Figure 2. Diagnostic features for the genus. (A,B) clypeus; (A) L. multicolor; (B) L. dodecius. (C,D) L. australis; (C) wings; (D) hind t4.

Figure 5. Ovipositor apex. (A) L. australis; (B) L. dodecius; (C) L. duckei; (D) L. exius.

Figure 6. Ovipositor apex. (A) L. ichilus. (B) L. multicolor; (C) L. tenuis; (D) L. venezuelanus.

Figure 7. (A,B) Head, frontal view. (A) L. dodecius; (B) L. ichilus (C-E, G) Mesosoma, lateral view. (C) L. duckei; (D) L. australis; (E) L. ichilus; (F) L. docedius male, propodeum; (G) L. exius; (H) L. multicolor, metasoma.