Colobaea punctata (Lundbeck, 1923)

Bratt, Albertus D., Knutson, Lloyd V., Murphy, William L. & Daniels, Anthony A., 2020, Biology, immature stages, and systematics of snail-killing flies of the genus Colobaea (Diptera: Sciomyzidae), with overviews of aspects of the tribe Sciomyzini, Zootaxa 4840 (1), pp. 1-64 : 43-47

Colobaea punctata

Egg (based on four specimens from Adra, Spain). Length 0.60–0.80 mm; greatest width 0.20–0.30 mm. Robust, anterior end smoothly rounded, dorsal surface slightly convex in lateral aspect, ventral surface strongly convex. Chorion finely punctate with coarse, reticulate pattern.

First-instar larva (based on 10 specimens from Adra , Spain). Length 0.60–0.96 mm; greatest width 0.12–0.20 mm. Basal rings of sensory papillae lightly pigmented; post-oral spinules long, slender, lightly pigmented. Segmental spinules sparse, lightly pigmented. Cephalopharyngeal skeleton brown, 0.08–0.09 mm long. Indentation index 72–81. Mouthhooks short, broad .

Posterior end with three pairs of marginal lobes and lateral protuberances; spinules on lobes small, lightly pigmented. Spiracular tubes 0.014 mm long. Float hairs short, slender.

Second-instar larva (based on 10 specimens from Adra , Spain). Length 1.0–2.0 mm; greatest width 0.3–0.5 mm. Anterior spiracles small, apical part slightly expanded, subcircular, 14–16 marginal papillae .

Cephalopharyngeal skeleton ( Fig. 11 ) 0.17 mm long. Indentation index 90. Mouthhooks long, slender; hook part large, sharp. Ventral arch with 18–20 teeth. Dorsal cornu with small, incomplete window; ventral cornu with large, complete window.

Segments III and IV with undivided ventral spinule patch. No spinules on lateral pads.

Posterior end with four pairs of lobes. Lateral pair largest, apices rounded, projecting anterior to margin of disc; ventral and ventrolateral pairs subequal, apices rounded, about half the size of lateral pair; dorsal pair very small. Mammillae present above bases of ventral lobes. No float hairs at margins of spiracular plates.

Third-instar larva (based on five specimens from Adra, Spain). Length 2.8–5.0 mm; greatest width 0.8–1.2 mm. Body form slender, spindle shaped, circular in cross section, not expanded or flattened posteriorly.Anterior spiracles with 14–16 marginal papillae, no prismatic spots, integument not closely enclosing each papilla ( Fig. 34 ).

Cephalopharyngeal skeleton ( Fig. 39–40 ) 0.38 mm long. Indentation index 83. Dorsal cornu of pharyngeal sclerite with large, elongate, complete window; ventral cornu with large, complete window; dorsal bridge prominent; mouthhooks large, ventrally directed. Ventral arch with 18–20 teeth.

Spinules sparse, not pigmented. Segments III and IV with ventral spinule patch, segment V with two-part patch, segments VI–XII with three-part patches. Lateral pads with spinules. No spinules or scales dorsally.

Posterior end with four pairs of lobes ( Fig. 18 ). Ventral and ventrolateral lobes large, subequal; lateral protuberances at anterior margin of disc ( Fig. 20 ); dorsal lobes very small. Mammillae at bases of ventral and ventrolateral lobes. Ventral and ventrolateral lobes and lateral protuberances with 3–4 rings of spinules. Peritremes, slit margins, and stigmatic scars darkly pigmented.

Puparium ( Figs 47–48 ) (based on 10 specimens from Adra , Spain). Length 2.7–3.7 mm; greatest width 1.3–1.5 mm Shaped to fit inside snail shells. Dorsal surface of first six segments flat and occluding shell, ventral surface of first six segments convex and appressed to outer surface of shell whorl, dorsal surface of last segments concave and appressed to inner surface of shell whorl, ventral surface of last segments not contacting shell. Body form robustly spindle shaped, widest in one-third to one-half distance from anterior end, narrowed to small posterior spiracular disc .

Anterior half of dorsal surface darkly pigmented, dark reddish brown; posterior half of dorsal surface light reddish brown. Integument of dorsal surface of first six segments thick, that of posterior surface thin, fragile, finely granular, wrinkled at segmental folds. Secondary integumentary folds apparent dorsally. Primary integumentary folds conspicuous on anterior half, less obvious on posterior half. Lateral intersegmental pads obscure, lateral longitudinal welts apparent.

Anterior spiracles small, protruding from dorsal surface of cephalic cap near angles; posterior spiracles lightly pigmented, protrudent. Lobes of posterior end slightly reduced and distorted.

Lundbeck (1923) described but did not figure the puparium of his new species C. punctata ; however, he emphasized the differences in shape of puparia found in Planorbarius corneus , Planorbis albus , Planorbis planorbis , and “ L. ovata var. peregra ” [= Radix peregra ] from the shape of puparia of C. pectoralis found only in Planorbis vortex . He then expanded upon his 13-line original description of the adult flies of C. pectoralis and C. punctata , noting that, “the specimens in our old collection of C. pectoralis , which Zetterstedt had seen, I found them to be the present species—I think he has had both species [ Denmark, Sweden] before him.” It is interesting to note that Lundbeck was motivated to describe his new species C. punctata (based on adult flies) because of results of his initial comparisons of immature stages of C. pectoralis and C. punctata , which reinforces our temerity in describing a new species of Colobaea based partly on immature stages.

Figures

FIGURES 9–12. Cephalopharyngeal skeletons: 9, Colobaea pectoralis (Zetterstedt), first-instar larva; 10, C. pectoralis, second-instar larva; 11, C. punctata (Lundbeck), second-instar larva; 12, C. deemingi Knutson & Bratt, second-instar larva.Abbreviations: DB, dorsal bridge; DC, dorsal cornu; HS, hypostomal sclerite; MH, mouthhook; PS, pharyngeal sclerite; VA, ventral arch; VC, ventral cornu. Measurement in mm.

FIGURES 32–35. Anterior spiracles, third-instar larvae: 32, Colobaea pectoralis (Zetterstedt); 33, C. deemingi Knutson & Bratt; 34, C. punctata (Lundbeck); 35, C. bifasciella (Fallén). Abbreviations: PrS, prismatic spot; StS, stigmatic scar. Measurement in mm.

FIGURES 38–39. Cephalopharyngeal skeletons of third-instar larvae: 38, C. americana Steyskal, lateral view; 39, C. punctata (Lundbeck). Abbreviations: AvP, anteroventral process of pharyngeal sclerite, DB, dorsal bridge, DC, dorsal cornu, DW, dorsal window, ES, epistomal sclerite, HS, hypostomal sclerite, LS, ligulate sclerite, MH, mouthhook, PB, parastomal bars, PS, pharyngeal sclerite, VA, ventral arch, VC, ventral cornu, VW, ventral window. Measurement in mm.

FIGURES 40–43. Cephalopharyngeal skeletons of third-instar larvae: 40, C. punctata, lateral view; 41, C. pectoralis, lateral view; 42, C. bifasciella (Fallén), lateral view; 43. C. deemingi Knutson & Bratt, lateral view. Abbreviations: AvP, anteroventral process of pharyngeal sclerite, DB, dorsal bridge, DC, dorsal cornu, DW, dorsal window, ES, epistomal sclerite, HS, hypostomal sclerite, LS, ligulate sclerite, MH, mouthhook, PB, parastomal bars, PS, pharyngeal sclerite, VA, ventral arch, VC, ventral cornu, VW, ventral window. Measurement in mm.

FIGURES 15–20. Posterior ends of third-instar larvae: 15, Colobaea americana Steyskal, caudal view; 16, C. bifasciella (Fallén), caudal view; 17, C. pectoralis (Zetterstedt), caudal view; 18, C. punctata (Lundbeck), caudal view; 19, C. deemingi Knutson & Bratt, caudal view; 20, C. punctata, lateral view.Abbreviations: DL, dorsal lobe, LP, lateral pad, M, mammillae, PaP, peri-anal pad, SpP, spiracular plate, SpT, spiracular tube, VL, ventral lobe, VlL, ventrolateral lobe. Measurement in mm.

FIGURES 44–48. Puparia, lateral and dorsal views: 44, Colobaea americana Steyskal, lateral view; 45, C. deemingi Knutson & Bratt, lateral view; 46, C. deemingi, dorsal view; 47, C. punctata (Lundbeck), lateral view; 48, C. punctata, dorsal view. Measurement in mm.