Phylloicus cressae Prather 2003

Barrios, Margenny C., Mendoza, María D. & Montoya, José V., 2020, Description of larva and pupa of Phylloicus cressae Prather 2003 (Trichoptera Calamoceratidae) from a montane forest stream in the peri-urban area of Caracas Venezuela, Zootaxa 4768 (4), pp. 579-588 : 580-587

Phylloicus cressae Prather 2003 .

Type material: VENEZUELA: Lara: Parque Nacional Dinira, Quebrada Las Pinetas , 09°46’19”N, 70°01’45”W, 1889 m, 22.vi.2001, Holzenthal, Blahnik, Paprocki, & Cressa ( UMSP), male .

Material examined: Venezuela, Miranda, Altos de Pipe , IVIC , Quebrada Manantial , 10°10.34’ N, 66°58.12’ W, 1600 m a.s.l., (05.v.2017), M. Barrios, M.D. Mendoza, J. V . Montoya, 9 encased larvae, 2 pupae ( UMSP); same, 6 encased larvae, 3 pupae ( MIZA-UCV) .

5 th instar larva: Body length mean = 16.19 mm (range 14.9–16.9 mm; n = 15).

Head capsule: Rugose, elongated in dorsal view, amber with yellow, smooth, ovoid muscle scars. Antennae short, 2-segmented, located between anterior margin of head capsule and eyes. Frontoclypeal apotome subtriangular, wider anteriorly, with weak constriction in middle and with 1 large ovoid yellow muscle scar centered in posterior half. Labrum with transverse row of 32 setae ( Fig. 1A ). Triangular ventral apotome nearly reaching posterior end of head. Mandibles each with 3 teeth, 1 large central apical tooth and 2 smaller subapicolateral ones bordering a mesal groove; inner side with median brushes ( Fig. 2 ). Labium wide basally, with fused submental sclerite subtriangular near base and 3 rounded apical lobes, pair of lateral palpigers bearing labial palps, central one larger than other two and terminated by silk gland opening, labial palps 3-segmented ( Fig. 1B ). Head chaetotaxy distributed as Fig. 1A as defined by Mathis (1997).

Thorax: Pronotum amber, with smooth, yellow, ovoid muscle scars posteriorly and posterolaterally; anterolateral extensions of pronotum elongated as pair of strong sclerotized hooks in dorsal view; anterior margin serrate; posterior and posterolateral edges black; 3 pairs of setae on anterior edge; 2 pairs on anterolateral extensions; 5 pairs of setae near lateral edges; and 2 pairs of setae near mid-dorsal ecdysial line ( Fig. 3A ). Mesonotum with central pair of irregular amber sclerites with yellow muscle scars anteriorly, anteromedial margins strongly sclerotized, posterior margins not clearly delimited. Paired setal areas (DSa) present, on each half DSa 1 with 1 short seta, DSa 2 with 1 long (DSa2 1) and 1 short seta (DSa2 2), DSa 3 on prominent anterolateral sclerite, with 6 long and 4–6 short setae ( Fig. 3B ). Metanotum membranous with paired setal areas, on each half DSa 1 with 1 short seta, DSa 2 with 1 long seta (DSa2 1) and 2 short setae (DSa2 2, DSa2 3), DSa 3 with 2 short and 6 long setae ( Fig. 3C ) as defined by Mathis (1997). Legs: Forelegs each with well-developed trochantin, tapered anteriorly, with 1 seta on basal lobe. Each tibia with stout subapicoventral spine. Tarsal claws each with stout basal seta, such that claw and seta appearing as 2 claws. Leg chaetotaxy in Fig. 4 as defined by Williams & Wiggins (1981).

Abdomen: Membranous, pale yellow. Gills each with 3 or 4 filaments, distributed as in Table 1. Segments III–VII with lateral lines composed of fine, pale setae. Segment VIII with 2 pairs of fine dorsal setae, 1 pair of fine lateral setae, and 1 pair of fine, shorter setae. Segment IX with 1 pair of thick long setae, followed by 3 pairs of fine, short setae in middle of posterior margin, 1 pair of dorsomedial thick setae and 1 pair of lateral setae. Anal prolegs each with very sclerotized hook and long setae.

Case of 5 th instar larva: Length mean = 22.98 mm (range = 21.9–23.5 mm; n = 15) in dorsal side. Flattened, built with fragments of leaves. Each case usually with 3 or 4 dorsal, and 3 ventral rounded or oval fragments ( Fig. 5).

Pupae: Body length mean = 12.3 mm (range = 10.3–13.3 mm; n = 5). General color yellowish brown.

Head: Mandibles falciform, well-developed with internal margin finely serrate, apex pointed ( Fig. 6A ). Each mandible with 2 thick, long basolateral setae. Maxillary palps each 5-segmented, length slightly exceeding bases of forecoxae; labial palps each 3-segmented, short, reaching middle of 3rd segment of maxillary palps. Labrum trapezoidal with base wider than apex, apical area with approximately 12 to 14 pairs of setae; clypeus with 3 pairs of lateral setae. Eyes large, 1 pair of setae in genal area anterior to eyes, another pair on frontal area, 3 pairs of setae posterior to eyes, and another pair on vertex between antennae. Antennal scapes each broad, with group of 5 setae on base and 2 long lateral setae followed by group of 3 short and fine setae on inner side; pedicel without setae; flagellum extremely long, 2x body length and coiled apically ( Fig. 6B ).

Thorax: Pronotum narrow, bearing 1 pair of setae. Mesonotum wide, with 3 pairs of dorsal setae, 1 anterior and 2 posterior. Metanotum smaller than mesonotum, with 3 pairs of setae, 1 pair on anterior margin, 2 pairs near posterior margin. Middle and hind leg tarsi each with row of fine, long setae, much more numerous on middle tarsi. Wing pads reaching abdominal segment V ( Fig. 6B ).

Abdomen: Hook plates on anterior part of segments III–VIII, elliptical, each with 2 hooks curved backward, shape varying according to body size and individual; segment I with 1 pair of sclerotized posterolateral lobes each having small hook plate with 3 tiny hooks curved backward; segment V with 1 pair of posterior hook plates, each with 4 hooks curved forward. Segments II–VII each with row of brown setae on posterior margin, these setae longer on segments II–IV, thicker and shorter on segments V–VII. One pair of short setae on anterior part of each segment IV–VII, and 1 pair on posterior part above row of setae on segments V–VII. Segment IX narrow, with 5 pairs of dorsal setae and 2 sclerotized spines apically; apical processes approximately as long as segment IX, each with long seta at midlength and 3 subapical setae ( Fig. 6B ). Abdominal gills with 3 or 4 filaments on each segment and distributed as in Table 1.

Taxonomic remarks. Some morphological characteristics are noticeable when comparing larvae of P. cressae with those described for other species in the genus. The main differences are visible in the color pattern of the head and thorax and their muscle scars, as well as in the mandibles and the chaetotaxy of the mesonotum and metanotum. The color of the larval head and thorax in P. cressae is amber with yellow muscle scars, while in other species ( P. obliquus Navás 1931 (Calvacante et al. 2020), P. camargoi Quintero & Calor 2011 (in Quintero et al. 2011), P. abdominalis ( Ulmer 1905) ( Huamantinco et al. 2005) , and P. lituratus (Rueda-Martín 2013)) head and thorax are dark brown with yellowish- brown or light brown ( P. camargoi ) muscle scars. The number of teeth on the mandibles also differs between P. cressae (3 teeth: 1 central large tooth, and 2 lateral teeth) and P. obliquus (2 well-developed teeth), but in P. camargoi , P. abdominalis , and P. pulchrus , the number and size of teeth are similar. The shape of the central sclerites of the mesonotum in P. cressae is triangular with posterior margins rounded, similar to P. obliquus and P. abdominalis , but in P. camargoi the mesonotum tends to be subquadrate and in P. lituratus it is subtriangular. Chaetotaxy of the mesonotum also differs from that of other species: P. obliquus has DSa1 with 1 pair of short setae, DSa2 is without setae, DSa3 with five pairs of long setae; P. camargoi , P. abdominalis , and P. lituratus have mesonota with DSa1 bearing 1 pair of short seta, DSa2 is with 2 pairs of short and 1 pair of long setae, DSa3 is with 5 short and 4 long pairs of setae. Metanotal chaetotaxy of P. cressae (DSa 1 is with 1 pair of short seta, DSa 2 is with 1 pair of long seta and 2 pairs of short setae, DSa 3 is with 2 pairs of short and 6 pairs of long setae) also differed from P. obliquus (DSa 1 is without setae, DSa 2 is with 1 pair of long setae, DSa 3 is with 5 long pairs of setae), P. camargoi (DSa 1 is with 1 pair of long setae, DSa 2 is with 2 pairs of long setae, DSa 3 is with 4 pairs of short and 2 pairs of long setae), and P. abdominalis (DSa 1 is with 1 pair of setae, DSa 2 is with 1 pair of long setae and 2 pairs of short setae, DSa 3 is with 5 pairs of long setae). Tarsal claws on all legs of P. cressae also differed from those of larvae of some species like P. obliquus with the tarsal claws simple.

The pupa of P. cressae can be distinguished from those of other Phylloicus species by the presence of 3 hooks on each of the plates on the posterior margin of segment I, 2 hooks on each hook plate on the anterior part of seg- ments III–VIII, and 4 tiny hooks on each posterior hook plate on segment V, while P. obliquus has 3 or 4 small hooks on each hook plate on segment I, 2 hooks on each hookplate on segment III, and 3 hooks on each anterior hook plate on segments IV and V, each posterior hook plate on segment V with 4 or 5 hooks, and on segments VI–VIII with 3 or 4 hooks. In the case of P. camargoi , each anterior hook plate of segments III–V, VII, and VIII, with 1–3 hooks ( V and VIII usually with 2 hooks), those on segment VI each with 2–3 hooks, and posterior hook plates on segment V with 2–4 hooks. For P. lituratus , all segments have each hook plate usually with 2 hooks and posterior hook plates on segment V each with 5 hooks. The pupa of P. abdominalis has 3 or 4 hooks on each hook plate.

Aquatic and riparian habitat: Larvae and pupae of Phylloicus cressae were found in a spring-fed first-or- der stream named Quebrada Manantial. This is a small mountain stream at 1600 m a.s.l. with a mean discharge of 0.8– 1 L. s-1. The bottom substrate was characterized by sand and gravel with interspersed leaf litter packets. The ranges of physico-chemical parameters were as follows: Temperature 18.14–21.19°C, dissolved oxygen 3.48–7.10 mg. L-1, and 37.4–76.4 %, pH 7.64–8.18, and conductivity 191.40–226.25 µS. cm-1 (values measured in situ using a YSI ProPlus multiparameter sonde). This creek is one of the least-disturbed streams in the region, even though it is located in the heavily impacted peri-urban area of Caracas. We did not find Phylloicus cressae in other streams nearby, like Quebrada Fernández Morán or Quebrada Guayabal which is where Quebrada Manantial empties its waters. Quebrada Guayabal is part of the Tuy River basin, one of the most disturbed and polluted watersheds in Venezuela ( Rodríguez-Olarte et al. 2018). Most of headwater streams of the peri-urban area of Caracas are strongly affected by direct inputs of untreated urban and industrial sewage and agricultural runoff, making them unfitted habitats for species of aquatic insects intolerant to pollution and habitat degradation, such as species of the genus Phylloicus . In Quebrada Manantial, riparian forest is mainly composed of Croton megalodendron (Euphorbiaceae) , Bunchosia armeniaca (Malpigiaceae) , Turpinia occidentalis (Staphyliaceae) , Piper brederelleri (Piperaceae) , Toxicodendrum occidentalis (Anacardiaceae) , Cupania sp. ( Sapindaceae ), Cecropia angustifolia (Cecropiaceae) , Ficus tonduzii (Moraceae) , Erythrina poppeyana (Fabaceae) , Persea caerulea (Lauraceae) , and introduced Syzygium jambos (Myrtaceae) , Citrus limon (Rutaceae) , and Coffea arabica (Rubiaceae) .

Biological notes: Phylloicus cressae is one of the most abundant macroinvertebrates in the headwater stream (pers. obs.). Larvae were usually found on or among submerged leaves of Ficus tonduzii , Erythrina poppeyana , Turpinia occidentalis , Cupania sp., Cecropia angustifolia , and Syzygium jambos , which are the most common tree species of the riparian forest of the headwater stream. In the field, pupae were found usually among leaf litter, rocks, dead wood, and fig fruits. Egg masses were found on leaves of Cupania sp. and C. angustifolia (pers. obs.). Phylloicus spp. are characterized by day-active adults; nevertheless, we could not find any evidence of activity of this species during the day. Adults emerged from pupae at the end of the afternoon, from 17h00 to 19h00 (this could be seen only in the laboratory); it is possible that they are active at these hours in nature for copulation, oviposition, or dispersal. While rearing pupae and adults in laboratory conditions, we observed that larval mortality occurred above 25°C (range of stream water temperature: 18.1–21.2°C).

Figures

FIGURE 1: Phylloicus cressae, larva; head capsule. 1A, dorsal; 1B, ventral. Head chaetotaxy in dorsal view, 1A: FC1–FC6 = frontoclypeal tactile setae, A1–A2 = anterior tactile seta, L1 = lateral tactile seta, posterolateral to stemmata, S2 and S3 = stemmatal tactile seta, P1–P4 = posterior tactile seta.

FIGURE 2: Phylloicus cressae, larva, mandibles. 2A, lateral view; 2B, ventral view.

FIGURE 3: Phylloicus cressae, larva; thorax, dorsal. 3A, pronotum; 3B, mesonotum; 3C, metanotum. Chaetotaxy of mesonotum and metanotum: DSa1 = tactile seta in dorsal Sa1, DSa2 = tactile setae (2 or 3) in dorsal Sa2, DSa3 = group of long and short tactile setae in dorsal Sa3.

FIGURE 4: Phylloicus cressae, larva; right thoracic legs I, II, III, posterior. 4A, foreleg; 4B, midleg; 4C, hind leg. Legs chaetotaxy: Coxa: 1 = posterior, dorsal, 3 = anterior, dorsal, proximal, 4 = anterior, dorsal, distal, 5 = anterior, median, 6 = anterior, median. Trochanter: 1 = posterior, median, 2 = posterior, ventral, distal. Femur: 1 = dorsal, median, 2 = dorsal, distal, 3 = posterior, distal, 4 = posterior, ventral, 5 = anterior, ventral, proximal, 6 = anterior, distal. Tibia: 2 = posterior, median, distal, 3 = posterior, dorsal, distal. Tarsus: 1 = posterior, ventral, distal, 2 = dorsal, distal, 3 = dorsal, distal.

FIGURE 6: Phylloicus cressae, pupa. 6A, mandibles, ventral; 6B, pupa body, dorsal.