Caenotus Cole

Metz, Mark A., 2003, Description of a new species of Caenotus Cole (Diptera: Scenopinidae) from Baja California Sur, Mexico, with a review of the genus, Zootaxa 223, pp. 1-11 : 3-8

Caenotus Cole

Caenotus Cole, 1923: 14 . Type species: Caenotus inornatus Cole, 1923: 16 by original designation. hospes Melander, 1950: 149 Type locality Organ Pipe Cactus National Monument, Arizona, USA. inornatus Cole, 1923: 16 Type locality Alamogordo, New Mexico, USA.

mexicanus Nagatomi & Yanagida, 1994: 159 Type locality 18 miles S.W. Santa Catarina, San Luis Potosi, Mexico.

minutus Cole, 1923: 15 Type locality Alamogordo, New Mexico, USA.

tanyrhynchus spec. nov. Type locality Arroyo San Gregorio, Baja California Sur, Mexico.

Caenotus tanyrhynchus spec. nov.

Etymology. tany­ (Greek, adjective) = long + rhynchus (Greek, noun, masculine) = snout, muzzle; “long mouth” referring to the extremely elongate proboscis of the species.

Diagnosis. This species is readily distinguished by the extremely elongate mouthparts. Other species of Caenotus have mouthparts that barely extend out from the oral cavity, while C. tanyrynchus has mouthparts as long as the head is high. C. tanyrhynchus is also covered with very long, filiform setae whereas other species of Caenotus are covered with much shorter setae.

Male. Head. Shiny black; covered with extremely fine and short pruinose­like setae, except along dorsal and posterior margin of compound eye. Ocellar tubercle raised on vertex, 1.33 times wider than high. Nearly holoptic, eyes separated by less than the width of one ommatidium above narrow frontal triangle. Inner eye margin smoothly curved around base of antenna, but not sharply indented. Ommatidia of compound eye subequal in size with no horizontal line demarcating upper and lower regions of ommatidia. Postocellar macrosetae long, most as long as and many longer than the length of the scape; filiform; black. Gena and ventral oral margin slightly extended ventrally; long, filiform black setose. Postgena long, filiform black setose. Occiput covered with fine and short setae; with long black setae laterally and ventrally. Antenna black, gold pruinose. Scape and pedicel with long black setae, setae 1.5 times longer than width of scape. Basal flagellomere much longer than wide, longer than scape; medial side extending longer than lateral; black; gold pruinose; infrequently setose dorsally at base. Style two segmented; first segment apical, length and width subequal, cylindrical; black; gold pruinose; lacking setae; second segment apical, sharply acuminate, three times longer than wide. Maxillary palpus black; one segmented; elongate, length _ height of head; cylindrical; gold pruinose; with long, filiform, black setae. Labrum and labium elongate; together subequal in length to height of head; black; black setose. Labellum not enlarged; circular, slightly longer than wide; ventral surface filiform, black setose.

Thorax. Shiny black; gold pruinose except scutum, dorsal scutellum, anepisternum, and anepimeron only shiny black. Pronotum, proepisternum, prosternum, scutum, dorsal anepimeron, and scutellum with long yellow, fine filiform setae admixed with long brown setae. Joint between prosternum and propleuron large and membranous. Scutal and scutellar macrosetae undifferentiated, if present. Legs. Dark brown, sparsely gold pruinose. Fore­ and midcoxae with long, filiform, brown setae anteriorly; hindcoxa with long, filiform, brown setae anterolaterally to posterolaterally; hindcoxal knob extremely reduced, present as a low rounded point. Wing. Membrane mostly hyaline, slightly brown tinged along veins; microtrichiose throughout; pterostigma pale brown; costa apparently circumambient; veins M1 and M2 arising separately from discal cell; vein M3 absent. Halter light, very pale gold, darker at base of stalk.

Abdomen. Tergites and sternites black, sparsely gold pruinose; long, fine filiform golden setose, with lateral setae and setae on basal segments longer. Modified setae on tergite 2 ( Fig. 2 ) composed of a single patch of shortly acuminate setae arranged in an ovoid pattern, longer than wide; some specimens with patch medially divided forming two bilaterally symmetrical, semicircular patches.

Terminalia. Tergite 8 unmodified, similar to previous segments; wider than long; anterior margin slightly narrower than posterior; with one pair of sensory setae; dark brown; sparsely gold pruinose; golden setose. Sternite 8 quadrate, wider than long, anterior and posterior margins subequal in width; dark brown; sparsely gold pruinose; fine filiform golden setose. Tergite 9, epandrium, ( Fig. 3 ) divided medially, right and left halves connected only by weakly sclerotized membrane; each half with a posteromedial flange of cuticle lacking setae; ventral surface sclerotized posterolaterally; dark brown, lateral edges dark yellow; sparsely gold pruinose; filiform black setose. Cercus ( Fig. 3 ) extending slightly beyond extension of hypoproct; black setose dorsally and apically. Hypoproct ( Fig. 3 ) truncate; setose ventrally and apically. Subepandrial sclerite strongly sclerotized laterally, otherwise membranous. Hypandrium large, minimal reduction from size of sternite 8; triangular, acuminate posteriorly; fused to gonocoxite posterolaterally, otherwise connection membranous; black, filiform setose ventrally. Gonocoxite ( Fig. 4­5 ) with a ventrolateral, acuminate projection; area of articulation with epandrium oriented vertically such that articulating surface faces laterally; dark brown; black, filiform setose ventromedially. Gonocoxal apodeme ( Fig. 4 ) extending anteriorly beyond anterior border of gonocoxite. Gonostylus ( Fig. 5 ) crescent­shaped when viewed laterally; curved dorsally at apex; apex dorsoventrally flattened, but acuminate when viewed dorsally; setose dorsally at base, otherwise ventrally setose. Aedeagus ( Fig. 4­5 ) brown with parameral sheath and apodemes reduced anteriorly; dorsal apodeme extremely short, essentially absent; ventral apodeme broadened laterally, short and truncated anteriorly, with lateral carinae; fused by a strongly sclerotized connection to gonocoxite laterally at base of gonocoxal apodeme; phallus with pair of dorsolateral projections anteriorly. Distal parameral sheath ( Fig. 4 ) bifurcate at base. Aedeagal apodeme ( Figs. 4­5 ) robust, roughly cylindrical, anterior end broadened laterally; posterior end broadened laterally and ventrally creating a basketshaped posterior face; with a sclerotized ring dorsally as connection for vas deferens; dorsally, ventrally, and laterally carinate from middle to anterior end.

Female same as the male except as follows.

Head ( Fig. 1 ). Dichoptic, frons at its narrowest width 2X that of the ocellar tubercle. Frons shiny black, small triangular area dorsad of antennae pruinose; short black setose. Parafacial shiny black adjacent to eye margin. Gena and postgena with some pale yellow setae. Proboscis longer, approaching 1.5 X height of head.

Thorax. Some specimens with more robust setae on postalar callous and scutellar margin, approaching the thickness of thoracic macrosetae.

Terminalia ( Fig. 6 ). Tergite 8 with length and width subequal; anterior margin straight; posterior margin with a narrow strip of cuticle connecting to tergite 9; dark brown; sparsely gold pruinose; black, filiform setose. Membrane between tergite 8 and tergite 9 glabrous. Sternite 8 ( Fig. 6 ) longer than wide; anterior margin straight, but anterolateral corners extended anteriorly; posterior lobe sclerotized, but short; black, filiform setose; posterior setae spaced more densely. Acanthophorites ( Fig. 6 ) joined narrowly at dorsum by narrow strip of tergite 9; 5 pairs of apically spatulate, robust b1 spines; 4 pairs of acuminate, fine b2 spines; short, black, filiform setose. Sternite 10 broader anteriorly, triangular; weakly sclerotized medially; posterior membranous, acuminate; ventrally brown; short, black fine filiform setose. Cerci ( Fig. 6 ) and hypoproct bulbous and membranous; minutely setose. Furca ( Fig. 6 ) hour­glass shaped with the anterior and posterior ends rounded. Spermathecal ducts and spermathecal sac duct ( Fig. 6 ) arising from a common gonopore on the membrane of the furca. Spermathecal duct wider basally, narrowing before terminating at the spermatheca; total length approximately nine furcal lengths. Spermatheca ( Fig. 6 ) longer than wide, wider basally; apically capitate; sclerotized; brown. Spermathecal sac ( Fig. 6 ) duct subequal in width to the base of the spermathecal duct basally, but flaccid, narrowing apically before spermathecal sac; total length approximately 1.5 furcal lengths. Spermathecal sac ( Fig. 6 ) membranous, longer than wide; length subequal to length of furca. Accessory glands originating from a common duct on furcal membrane; approximately 5 furcal lengths; flaccid, ribbon like.

Distribution. Baja California Sur, Mexico.

Ecology. All specimens were labeled as collected in Malaise traps except two (MEI 143926, MEI 143923) without a collecting method associated with the labels and one (MEI 143928) taken in a “cereal bowl pit trap”. The very elongate mouthparts ( Fig. 1 ) suggest flower feeding and some specimens had several pollen grains on their bodies from at least two plant species.

Type material. Holotype male (MEI 143931), “ MEXICO:Baja Calif. Sur. Rcho. Tablon 13km. S. Guillermo Prieto, IV­16/18 ­1983”, “M.S. Wasbauer Collector.” Paratypes: Mexico, Baja California Sur: 1 male (MEI 143923), 6 females (MEI 143924 – 143929) same data as holotype; IV­14/18 ­1983; 2 females (MEI 143921 ­ 143922) Arroyo San Gregorio, 13 air km WNW La Purissima, IV­24/26 ­1983, all collected by M.S. Wasbauer and deposited in the California State Collection of Arthropods at the California Department of Food and Agriculture: 1 male (MEI 143920) Arroyo San Gregorio, 13 air km WNW La Purissima, IV­24/26 ­1983 collected by M.S. Wasbauer and 2 females (143932 – 143933) same data as holotype except one female (MEI 143933) collected by C & E Slansky deposited in the United States National Museum of Natural History: 1 male (MEI 143930) 9.2 mi. SE Guerrero Negro, III­23­1981, D. Faulkner & F. Andrews; deposited in the San Diego Natural History Museum.

Figures

FIGURE 1. Caenotus tanyrhynchus spec. nov., three quarter view of female head.

FIGURE 2. Caenotus tanyrhynchus spec. nov., dorsal view of male tergite 2 showing circular patch of specialized setae.

FIGURE 6. Caenotus tanyrhynchus spec. nov., female terminalia. ac, acanthophorite; ag, accessory gland; b 1, robust spines of the acanthophorite; b 2, fine spines of the acanthophorite; c, cercus; f, furca; h, hypoproct; S 8, sternite 8; sp, spermatheca; spd, spermathecal duct; ss, spermathecal sac; ssd, spermathecal sac duct.

FIGURES 3 ­ 5. Caenotus tanyrhynchus spec. nov., male genitalia. 3, Dorsal view of male epandrium, setae not illustrated on left side for clarity; 4, Dorsal view of gonocoxite and aedeagal apparatus, setae on dorsal gonostylus not illustrated for clarity; 5, Lateral view of gonocoxite and aedeagal apparatus. aa, aedeagal apodeme; c, cercus; ga, gonocoxal apodeme; gs, gonostylus; h, hypoproct; ps, parameral sheath.