A new species of Manoa from Everglades National Park

J. N. Am. Benthol. Soc., 2002, 21(2):314–325 q 2002 by The North American Benthological Society

A new species of Manoa (Diptera:Chironomidae) from Everglades National Park RICHARD E. JACOBSEN1

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SUE A. PERRY

South Florida Natural Resources Center, Everglades National Park, Homestead, Florida 33034 USA Abstract. Manoa pahayokeensis n. sp. is described from, and diagnoses are provided for, adults, pupal exuviae, and presumptive larvae collected from the Taylor Slough and Chekika areas of Everglades National Park, Florida. The generic description of Manoa is emended to accommodate M. pahayokeensis. Diagnostic autapomorphic character states for the genus include: for females, the medially divided floor under the vagina; for pupae, the elongate thoracic horn with characteristic tracheation, and the spine-like taeniae on the anal lobes; and for larvae, the stout, posteriorly curved procerci that arise close together from a posteromedian tubercle. Our collections are the first record of this rarely encountered tropical genus in North America and highlight the tropical component of the Everglades chironomid fauna. All specimens were collected from shallow-water marsh sites subject to water-level fluctuation and seasonal drying. Collection records for Manoa suggest the genus originated in Gondwanaland and arrived in the Nearctic either by northerly dispersal from South America or by tectonic vicariance events and dispersal from Africa. Key words: geography.

Chironomidae, Pseudochironomini, Manoa, Everglades National Park, taxonomy, bio-

The Everglades are noteworthy among large wetlands for their unique mix of temperate and tropical biota. The flora is dominated by tropical species, whereas most of the vertebrate fauna, aside from wading birds, are recent colonists from the temperate southeastern coastal plain (Gunderson and Loftus 1993). The invertebrate fauna in the Everglades is poorly known, but surveyed insects such as the Odonata (Paulson 1966) and Lepidoptera (Lenczewski 1980) include both Neotropical and temperate Nearctic species. Our surveys of Chironomidae in Everglades National Park indicate that the midge fauna is made up largely of Holarctic and cosmopolitan genera, but also includes several species in genera with primarily Neotropical distributions such as Goeldichironomus Fittkau, Beardius Reiss & Sublette, Endotribelos Grodhaus, and Polypedilum (Asheum) (Sublette & Sublette) (Jacobsen and Perry 2000, REJ and SAP, unpublished data). Perhaps the most interesting discovery, on account of its unusual morphology, Gondwanan origin, and the rarity of the genus in collections worldwide up to this point, is a new species of Manoa Fittkau. Fittkau (1963) erected the genus Manoa for an Amazonian species, M. obscura Fittkau, with unusual larval and pupal adaptations for water1

E-mail address: [email protected]

level fluctuations in shallow-water habitats. Sæther (1977b) described the distinctive features of the female and attempted to define Manoa morphologically when constructing a phylogenetic scheme for the Chironominae. Recently, Andersen and Sæther (1997) described the adults of Manoa tangae from a small mountain stream in Tanzania, a discovery that suggested the genus was in existence prior to the separation of Africa from South America. Our discovery of M. pahayokeensis n. sp. from shallow-water sites around Taylor Slough and northeast Shark River Slough is the first record of Manoa from North America. Methods The pupal stage was associated with adults through the fortuitous collection of a pharate male encased in its pupal skin. The presumptive larval association is based upon: 1) larval occurrence only in samples from the type locality that had numerous pupal exuviae and several adults of M. pahayokeensis, 2) their larval morphology not matching that of other Pseudochironomini collected during extensive surveys of marl prairie habitats in Everglades National Park, and 3) the larvae showing strong morphological affinity to larvae of M. obscura, particularly in head capsule features and in the distinctive morphology of the procerci. All specimens were collect-

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FIGS. 1–5. Manoa pahayokeensis n. sp., male. 1.—Head, frontal view. 2.—Labial palp. 3.—Hypopygium, left side: dorsal view, right side: ventral view with tergite IX removed. 4.—Superior volsella, dorsal view. 5.— Inferior volsella, dorsal view.

ed by the senior author while sampling for pupal exuviae at the water surface with a dipping pot and 125-mm-mesh sieve, preserved in 95% ethanol, and mounted, either uncleared or after clearing with KOH, in euparal. Morphological terminology and abbreviations follow Sæther

(1980), except taeniae and taeniate are used to designate and describe the flattened anal lobe setae in the pupa as suggested by Langton (1994), and terms for cuticular projections of pupae follow Langton (2000). Measurements generally follow Soponis (1977). The inferior and

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superior volsella lengths were measured from their medial junction with the gonocoxite to their apices. Measurements are reported as a range, followed by the mean when sample size n . 3, followed by n in parentheses. All measurements are in micrometers unless stated otherwise. The holotype of Manoa pahayokeensis n. sp. is in the Zoologische Staatssammlung, Munich, Germany. Paratypes have been deposited in the Everglades Region Collection Center, Everglades National Park, and the Zoological Museum, University of Bergen, Norway. Genus Manoa Fittkau Manoa Fittkau 1963: 373; Sæther 1977a: 156; Andersen and Sæther 1997: 311. Emended description Male and female imago. The generic descriptions for adults by Fittkau (1963), and emended by Sæther (1977b) and Andersen and Sæther (1997), can be further emended as follows: Antennal ratio 1.2–2.4. Palp length about 1–2 times height of eyes, palpomeres long, normal; palpomere 3 with 2–4 subapical sensilla clavata. Wing without or with reduced anal lobe. Weak pseudospurs present on ta1–4 or absent. Pulvilli small or absent. Male tergite IX with or without a median longitudinal seta-free band. Transverse sternapodeme convex or slightly concave with weak oral projections. Pars ventralis absent or represented by 2 triangular lobes basolaterally fused with gonocoxite. Superior volsella with short, ventral digitus devoid of microtrichia and setae, or digitus absent. Median volsella vestigial or tubercle-like, with microtrichia and 1–2 apical, strong setae. Sternite VIII forms floor carrying numerous setae under anterior and lateral parts of vagina; floor with shallow or deep, triangular, caudomesal incision. Notum slightly longer than, to almost twice as long as, seminal capsules. Spermathecal ducts straight or with loop. Pupa. The description by Fittkau (1963) is emended as follows: Small, 2.6–4.5 mm; exuviae pale yellow to nearly colorless. Cephalothorax. Frontal setae and cephalic tubercle absent. Frontal warts low, rounded, medially abutting, with or without a digitiform apical extension. Thoracic horn exceptionally long, slender, gradually tapering to a smooth or toothed apex. Tracheoles extend outward from

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tracheal bundle in a fascicle, then split apart and run along the inner horn surface. Two median antepronotals, 3 long precorneals, and 1 or 2 pairs of dorsocentrals present. Abdomen. Tergite I bare; II with anterior transverse band or 2 medially separated anterior fields of shagreen; III–VI with anterior transverse band of stronger shagreen, V–VI also with anterolateral and posterior fields of scattered points; tergites VII and VIII with diffuse anterior and often posterior fields of points. Posterior margin of tergite II with either a single continuous row of recurved hooklets or with 2–3 rows of recurved hooklets on conjunctive II/III. Conjunctives III/IV and IV/ V with 2–4 rows of recurved hooklets, all others bare. Pedes spurii A and B absent. Anal comb comprised of a small group of teeth. Abdominal setation: Segment I with 2–3 D, 0 or 3 L, and 2 V seta; II with 3 D, 3 L, and 2 V setae; III–VI with 3–4 D, 3 L, and 2–3 V setae; VII with 3–4 D, 3 L, and 2 V setae; VIII with 1–2 D, 0 or 5 L, and 1–2 V setae. Anal lobe about as wide to wider than long, bare or with 1 pair of dorsal setae. Anal lobe taeniae reduced in length, sclerotized, and either coalesced into a stout terminal horn-like armature or forming a comb of 4–10 spines. Male genital sheaths extend beyond anal lobe. Larva. The description by Fittkau (1963) is emended as follows: Body segments VIII and IX with or without short, dorsoposteriorly directed lateral tubules arising from the posterior pleura. Procerci stout, digitiform and posteriorly curved, length 2–6 times width, arising close together from a broad basal tubercle that overhangs segment XIII. Anal tubules elongate, about 1⁄th length of body and extensively tracheated, or shorter than posterior parapods, digitiform, not extensively tracheated. Manoa pahayokeensis Jacobsen n. sp. (Figs 1–21) Type material Holotype: Male (slide mounted in euparal), Florida, Dade Co., Everglades National Park, Taylor Slough Basin, marsh bordering Taylor Slough along road to Royal Palm 1.6 km south of Florida State Road 9336, 28.x.1998. Paratypes: Same as holotype: 2 males, 1 female, one 4th-instar larva, one 4th-instar larval

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FIGS. 6–9. Manoa pahayokeensis n. sp., female. 6.—Thorax, lateral view. 7.—Wing. 8.—Genitalia, ventral view. 9.—Genitalia, lateral view.

exuviae; same except 3 males, 2 females, 1 pharate male with pupal exuviae, 9 pupal exuviae, one 3rd-instar larva, one 3rd-instar larval exuviae, 16.x.1998; as previous except along L-31W canal about 400 m east of Taylor Slough, 1 pupal exuviae, 7.x.1998; as previous except Shark River Slough Basin, Chekika, marl prairie along SW 237 Avenue, 1.6 km north of Chekika Park entrance, 1 male, 13.iii.1999. Diagnosis Males of M. pahayokeensis can be distinguished from males of the other known species by the absence of a ventral digitus on the superior volsella, the absence of a pars ventralis,

the vestigial median volsella, the convex shape of the transverse sternapodeme, the lack of a seta-free band on tergite IX, and their lower antennal ratio (1.2 versus 1.9–2.3). Both males and females have small pulvilli and slender pseudospurs, character states that are not found in the other 2 Manoa species. Pupae of M. pahayokeensis have well-developed anal lobes with separated terminal spine-like taeniae, rounded cephalic tubercles, and the thoracic horn is 1.0–1.2 mm long. In M. obscura, the only other species with described immature stages, the anal lobes are reduced and the terminal spine-like taeniae are fused together into a large spur, the apex of the cephalic tubercles are digitiform, and the thoracic horn is approximately 3 mm long. Lar-

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vae of M. pahayokeensis, like M. obscura, possess large curved procerci arising from a posteromesal tubercle on abdominal segment XII, but they differ from M. obscura in lacking lateral tubules on abdominal segments VIII and IX and in having anal tubules that are shorter than the posterior parapods. Etymology Pa-hay-okee is the Seminole name for the Everglades and is best translated as ‘‘grassy lake’’. Description Male imago (n 5 7–8, unless stated otherwise) Total length 2.26–2.49, 2.36 mm. Wing length 1.06–1.25, 1.15 mm. Total length/wing length 1.90–2.23, 2.06. Wing length/profemur length 2.16–2.41, 2.29. Head (Fig. 1). AR 1.21–1.31, 1.25 (5). Terminal flagellomere 363–392, 376 (5). Temporal setae 12–15, multiserial. Frontal tubercles absent. Clypeus with 5–10, 8 setae. Interocular distance 197–216, 206 (5); head width 343–350, 347 (5), HIR (head width to interocular distance) 1.60– 1.78, 1.68 (5). Tentorium 96–118, 108 long, 12–

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16, 14 wide. Stipes 92–114, 101 (5) long. Palp segments (Fig. 2) 1–5 lengths: 19–22, 20; 22–27, 25; 29–50, 42; 53–70, 63 (6); 62–86, 77 (5). Third palpal segment with 2–3, 2 lanceolate sensilla clavata. Thorax. Antepronotal lobes reduced, separated medially, each lobe with 1–3, 2 lateral setae. Scutum overhangs antepronotum: dorsocentrals 5–8, 7 in single row; prealars 1–3, 3; supraalars 1; acrostichals 9–13, 11. Scutellum with single row of 2–4, 3 setae. Wing. VR 1.18–1.26, 1.24. No apparent anal lobe. Microtrichia coarse, visible at 1003. Costal extension 48–84, 62 long, with 0–2, 0 setae, terminal marginal seta length 33–47, 40. Brachiolum with 1–2, 1 setae; R with 1–4, 2 setae, R1 with 0–1, 0 seta, R213 with 0 setae, R415 with 0– 4, 1 setae. Squama bare. Legs. Tibial spur lengths: front 26–53, 37 (5); middle 30–35, 32 and 33–36, 34; hind 30–36, 33 and 35–40, 37 (5). Tibiae apex widths: front 27– 34, 31, middle 30–35, 33, hind 33–38, 35. Sensilla chaetica absent; slender pseudospurs present on ta1–4 of all legs. Small pulvilli present. Lengths and proportions of legs (n 5 4, unless indicated otherwise):

ta1

468–534, 502 (7) 524–599, 559 (7) 466–549 (3) 517–573, 548 (7) 483–551, 522 (7) 269–314, 291 556–627, 590 (7) 540–620, 587 (7) 351–405, 382

ta 2

ta 3

ta 4

219–255 (3) 108–130, 121 172–192, 184

179–202 (3) 89–101, 97 144–166, 156

122–139 (3) 60–70, 66 85–98, 91

ta 5

LR

BV

SV

BR

72–82 (3) 54–60, 58 62–70, 68

0.89–0.94 (3) 0.54–0.58, 0.56 0.64–0.65, 0.65

2.43–2.51 (3) 3.93–4.08, 4.00 3.05–3.29, 3.15

2.03–2.13 (3) 3.53–3.81, 3.70 3.08–3.15, 3.11

2.7–3.9 (3) 2.7–3.7, 3.1 3.1–3.6, 3.4

Abdomen. Number of setae on tergites I–VIII: 18–26, 21; 19–33, 25; 27–36, 31; 26–37, 31; 27–34, 31; 25–33, 29; 16–30, 24; 16–23, 20. Number of setae on sternites I–VIII: 0; 1–3, 2; 5–15, 10; 10– 17, 13; 9–14, 13; 10–14, 12; 10; 11–18, 15. Hypopygium (Fig. 3). Tergite IX truncate, without anal point or median longitudinal setafree band, with 24–35, 29 setae. Laterosternite IX with 1–2, 2 setae. Transverse sternapodome 10–25, 16 wide, convex, lacking oral projections. Phallapodome 72–82, 77 long. Gonocoxite 114–

125, 119 long; superior volsella (Fig. 4) 48–57, 53 long, digitus absent, dorsal surface with fine basal microtrichia and 2–4 setae, ventral surface with numerous long microtrichia and 2–4 apical setae; inferior volsella (Fig. 5) pediform, 54–64, 60 long, with medial and dorsal setae; median volsella vestigial, a low mound 1–3, 2 high, with 1–2 apical setae. Gonocoxite with low, rounded basimedial lobe but lacking pars ventralis. Gonostylus 68–88, 79 long. HR 1.33–1.68, 1.53; HV 2.68–3.32, 3.02.

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Female imago (n 5 4, unless stated otherwise) Total length about 1.95–2.17, 2.07 mm. Wing length 1.00–1.16, 1.06 mm. Total length/wing length 1.87–2.12, 1.96. Wing length/profemur length 2.33–2.66, 2.47. Head. AR 0.30–0.35, 0.33. Length of flagellomeres: 50–52, 51; 45–47, 46; 44–48, 46; 41–49, 45; 37–47, 43; 70–78, 75. Temporal setae 13–15 (3), multiserial. Clypeus with 7–10 (3) setae. Interocular distance 156–158 (2), head width 304– 309 (2), HIR 1.95–1.96 (2). Tentorium 88–98 (3) long, 12–13 (3) wide. Stipes 102 (2) long. Palp segment lengths: 18–22 (3); 23–30 (3); 34–42, 38; 53–62, 57; 72–83 (3). Third palpal segment with 2–4 (3) lanceolate sensilla clavata. Thorax (Fig. 6). Antepronotal lobes reduced, separated medially, each lobe with 1–2, 2 lateral setae. Scutum overhangs antepronotum, dorso-

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centrals 10–12, 11 in single row, including 2–5, 4 setae anterior to parapsidal suture; prealars 2– 3, 2; supraalars 1; acrostichals 9–12, 10. Scutellum with single row of 4–5, 4 setae. Wing (Fig. 7). VR 1.22–1.31, 1.27. No apparent anal lobe. Microtrichia coarse, visible at 1003. Costal extension 53–84, 70 long, with 2–6, 4 setae, terminal marginal seta 40–49 (3) long. Brachiolum with 1 seta; R with 7–10, 8 setae; R1 with 3–7, 5 setae; R213 with 0 setae, R415 with 8– 13, 10 setae. Legs. Tibial spur lengths: front 26–31, 28; middle 30–34, 32 and 31–36, 34; hind 32–37, 35 and 38–41 (3). Tibiae apex widths: front 30–32, 31; middle 31–35, 34; hind 34–38, 37. Small pulvilli present on ta5. Sensilla chaetica absent; slender pseudospurs present on ta1–4 of all legs. Lengths and proportions of legs:

Fe

ti

ta1

ta 2

412–448, 428 463–492, 478 514–563, 535

450–495, 472 431–475, 453 490–533, 511

434 (1) 234–262, 247 323 (1)

186 (1) 89–98, 93 142 (1)

ta 3

ta 4

141 (1) 72–80, 76 134 (1)

97 (1) 49–53, 51 71 (1)

ta 5

LR

BV

SV

BR

61 (1) 48–50, 49 53 (1)

0.89 (1) 0.53–0.56, 0.54 0.61 (1)

2.80 (1) 4.33–4.42, 4.38 3.55 (1)

2.13 (1) 3.67–3.87, 3.78 3.39 (1)

2.9 (1) 2.0–2.6, 2.3 2.6 (1)

Abdomen (n 5 2). Number of setae on tergites I–VIII: 14–20, 12–21, 18–24, 19–28, 22–30, 18–27, 14–22, 9. Number of setae on sternites I–VIII: 0, 1, 7–11, 9–19, 25–26, 20–29, 23–24, 30–34. Genitalia (Figs 8, 9). Sternite VIII forms 44–50 (3) long anterior and posterolateral floor ventral to the vagina, floor with approximately 25–30 setae and with median, 18–23 (2) deep, Vshaped notch. Tergite IX with 18–24, 21 setae; gonocoxite IX with 1–2, 2 setae. Cercus 48–52, 49 long. Seminal capsules 53 (1) long including 8–10 (3) mm long, collar-like neck; 29 (1) wide; apparently without microtrichia. Spermathecal ducts straight and usually with special secretory cells apparent. Notum 79–92 (3) long. Pupa (n 5 10) Total length 2.67–3.10, 2.84. Nearly colorless, with pale yellow pigmentation on the leg, wing and antennal sheaths, frontal apotome, parater-

gites VII–VIII, and the terminal spine-like taeniae of the anal lobes. Cephalothorax. Antennal sheath usually with minute pearl row above pedicle. Frontal setae and cephalic tubercles absent. Frontal warts low, rounded, often medially abutting. Antepronotum with 2 medial setae: 46–96, 71 and 40–70, 56 long. Thoracic horn (Fig. 10) elongate, 1.00– 1.20 mm long, widest at base and gradually tapering to a smooth, rounded apex. Tracheoles extend outward from tracheal bundle in a fascicle, then split apart at about 1⁄12th horn length, attach to the inner surface of the thoracic horn, and run along the remaining length of the thoracic horn in an orientation largely parallel to each other. Basal ring of thoracic horn circular to slightly elliptical, 20–24, 22 long, with 1 tracheal branch 14–18, 16 wide. Anterior precorneal seta (Pc1), 62–82, 73 long, Pc2 52–79, 64 (9)

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FIGS. 10–14. Manoa pahayokeensis n. sp., pupa. 10.—Thorax, lateral view. 11.—Tergites I–VI. 12.—Spines on conjunctive II/III. 13.—Tergites VII–IX and anal lobes. 14.—Anal comb on tergite VIII, 2 views.

long, Pc3 48–66 (2) long. Surfaces along dorsomedian suture smooth. Anterior dorsocentral seta (Dc1) stiff, hair-like, 14–24, 19 (9) long; Dc2 hair-like, 40–66, 53 (8) long; Dc3 stiff, hairlike, 10–14, 12 long; Dc4 hair-like, 31–42, 38 (8) long. Dc4 often anterior to Dc3. Distance between Dc1 and Dc2 11–18, 13; between Dc2 and Dc3 149– 192, 169; between Dc3 and Dc4 5–10, 6. Abdomen (Figs 11–14). Tergite I bare; II with

anterior transverse band of shagreen, band occasionally broken medially into 2 fields; III–VI with anterior transverse band of strong shagreen, V–VI also with anterolateral and posterior fields of scattered smaller points; VII with diffuse anterior fields and small posteromedian fields of fine points; VIII with anterior fields of small scattered points and occasionally with group of points extending medially from anal

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comb along posterior margin. Sternites I–II bare; III bare or with scattered, fine anterior points; IV with anterior to median field of scattered points; V with anterior field of points and point rows and posteromedial field of points, fields often extend toward each other as finer, scattered points; VI with wide anterior field of points that diminishes posteriorly or with wide anterior and posterior point fields; VII with scattered anterior points and occasionally a few points at posterior margin; VIII bare or with few scattered points. Hook row absent on II. Conjunctives II/III–IV/V with 2–4 rows of recurved hooklets (Fig. 12), all others bare. Pedes spurii A and B absent. Anal comb (Fig. 14) usually comprised of a small group of 2–3 teeth and 2– 28 smaller points, point field extends medially along posterior margin of VIII when numerous. Longest tooth 8–13, 11. Abdominal setation: Segment I with 2 D, 0 L, and 2 V seta; II with 3 D, 3 L, and 2 V setae; III–VI normally with 4 D, 3 L, and 3 V setae; VII with 3–4 D, 3 L, and 2 V setae; VIII with 1 D, 5 L, and 1 V setae. L1 and L3 of VII and L1, L3, and L4 of VIII are flattened and lanceolate. Anal lobe wider than long, tapered base; with 1 pair of dorsal setae. Apex of anal lobe with a comb of 4–10, 5 spine-like taeniae, longest 32– 49, 43. Larva, 4th instar (n 5 2, unless stated otherwise) Body slender, length of early 4th instar 3.22 mm (1). Head capsule light amber with brown mentum and inner mandibular teeth; length 0.22–0.23 mm. Head dorsum (Fig. 15). With frontal apotome, clypeus, and labral sclerite 2 present. Antenna (Fig. 16). 5-segmented. AR 0.78–0.86. Segment lengths: 29–31, 11, 11–12, 8–9, 3.5–4. Basal segment 13 wide; distance from base to ring organ 7–8, to basal setal mark 8, to distal mark 12–13. Blade 21–23 long, reaching to apex of 3rd segment; accessory blade 12–13 long. Lauterborn organs large, 10–11 long; segment 2 apical style 6 long. Labrum. SI plumose, arising from common base; SII narrow, apically plumose. Pecten epipharyngis composed of 3 digitiform plates, with at least 7 chaetulae laterales and 2 chaetulae basales. Seta premandibularis simple; premandible 52–53 long, bifid, with brush. Mentum (Fig. 17). Width 80–83. With rounded median tooth and 5 pairs of laterals, 1st lateral

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tooth notched laterally. Ventromental plates almost touching medially, width 72–74, length, including base, 29–35, with 45–46 striae. Postmentum 114–118 long. Seta submenti simple, 15 (1) long. Maxilla (Fig. 18). With 1 long lacinial chaeta. Mandible (Fig. 19). Length 89–94; dorsal tooth and pectin mandibularis absent; apical tooth pale, with 4 dark, pointed, inner teeth. Outer margin smooth, mola with 2 long spines, seta subdentalis long, slender, curved, inserted on dorsal side of mandible, seta interna with 2 major trunks, each extensively branched. Body. Without conspicuous setae. Long claws of anterior parapods smooth, short claws with a few minute inner teeth. Lateral tubules absent. Procerci (Figs 20, 21) digitiform, posteriorly curved, height 60 (1), width 24 (1), with 5–6 subapically inserted anal setae, longest seta 156–170 (1) long. Procerci arise close together from a broad base that overhangs segment XIII. Anal tubules of normal size, digitiform; ventral 60–63 (1) long, 21–24 (1) wide; dorsal 66 (1) long, 24 (1) wide. Discussion Systematics Within Sæther’s (1977b) phylogeny of the Chironominae, the Pseudochironomini were distinguished by the lack of wing membrane setae in the adults, and the short Lauterborn organs and narrow, elongate, closely situated ventromental plates with parallel striations in the larvae. Information pertinent for determining the inclusion of, and relationships between, several genera tentatively placed within the Pseudochironomini was not available at that time. However, Manoa, Riethia Kieffer, and Pseudochironomus Malloch were grouped together by their mutual lack of a true anal point (though an analogous structural development of tergite IX, termed a ‘‘caudal projection’’ by Sæther 1977b, is present in some Pseudochironomus spp.) and lack of a digitus (‘‘2a’’) on the superior volsella of the male hypopygium. Manoa and Riethia were tentatively grouped together based on their sharing a deeply divided floor under the anterior part of the vagina (though only confirmed for Manoa), absence of pars ventralis, and reduction of the antepronotum. However, Riethia does not have a floor under the vagina (P. Cranston, Uni-

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FIGS. 15–21. Manoa pahayokeensis n. sp., larva. 15.—Head, dorsal sclerites. 16.—Antenna. 17.—Mentum. 18.— Maxilla. 19.—Mandible. 20.—Posterior abdomen with posterior parapods retracted, lateral view. 21.—Procerci, anterior view.

versity of California-Davis, Davis, California, personal communication). Furthermore, the triangular basimedial lobes on the gonocoxites of M. obscura and M. tangae are now considered to be pars ventralis (Andersen and Sæther 1997) and the existence of both character states within the genus indicates this character is uninformative for resolving phylogenetic relationships. Andersen and Sæther (1997) suggested that distinguishing adults of Manoa from Riethia had

become potentially problematic since the discovery of M. tangae because neither genus showed a clear, definitive autapomophy in the adult stage. The lack of squamal setae and dorsal eye elongation were originally considered to be autapomorphies for Manoa (Sæther 1977b). After the discovery of M. tangae, the distinction between the 2 genera rested on the relative degree of expression of character states (0–6 squamal setae for Manoa versus fully fringed squa-

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ma for Riethia, no or only slight dorsal eye elongation for Manoa versus long elongation for Riethia), rather than the presence or absence of character states. Manoa tangae apparently was placed in Manoa on the basis of its greater overall similarity to M. obscura, particularly with respect to the morphology of the male hypopygium (Anderson and Sæther 1997). Considering Cranston’s observations on the female genitalia of Riethia, the divided floor under the vagina of M. tangae and its congeners not only is of greater diagnostic value than the hypopygium, but it appears to be an autapomorphy for the genus. The adults of M. pahayokeensis share character states with M. obscura and M. tangae for different features. Manoa pahayokeensis resembles M. obscura in having bare squama and no distinct elongation of the eyes, yet also has supraalar and antepronotal setae and a relatively smaller overhang of the scutum as in M. tangae. The association of pupal exuviae with adults of M. pahayokeensis helps to corroborate the generic placement of the adults, and allows an assessment of the relative value of different pupal characters for generic diagnosis. Pupae of M. pahayokeensis differ from those of M. obscura in having separated, spine-like taeniae on the anal lobe and in lacking a distinct single hooklet row across the apex of tergite II. This latter character state is rare in the Chironominae, being found only in Rheomus Laville & Reiss, Anuncotendipes Cranston, and some species of Cryptotendipes Lenz. Pupal synapomorphies for M. pahayokeensis and M. obscura that may serve to define Manoa morphologically include the elongate thoracic horn with characteristic tracheation and the modified, spine-like taeniae on the anal lobe. The presumptive association of the larva of M. pahayokeensis, though properly regarded as tentative at this time, is sufficiently reliable to allow evaluation of some larval characters found in Manoa and other Pseudochironomini for their potential importance in determining taxonomic boundaries and phylogenetic relationships. Larvae of M. pahayokeensis differ notably from M. obscura in lacking extensively tracheated lateral tubules and elongated anal tubules. However, both species show strong similarity in head capsule morphology, including sharing the following character states not found in other Pseudochironomini (3 Pseudochironomus spp.) in Everglades National Park or in other Pseudochironomus spp. larvae described from the Nearctic

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(Sæther 1977a): mandible with basal inner tooth pointed; maxilla with a single, elongate, pointed lacinial chaeta; antenna short with large Lauterborn organs; and mentum with 5 pairs of lateral teeth that decrease regularly in size laterally, and 1st laterals with only a shallow lateral notch. Though the procerci of M. obscura are much larger than those of M. pahayokeensis, both species have stout, posteriorly curved procerci that arise close together from a posteromedian tubercle that overhangs the terminal abdominal segment. In their description of the larval morphology of Pseudochironomus, Pinder and Reiss (1983) noted that, unlike the Chironomini, the seta subdentalis was inserted on the ‘‘inner’’ (dorsal) side of the mandible rather than the ‘‘outer’’ (ventral) side. This character state is also found in all known larvae of Manoa and Riethia (P. Cranston, personal communication), suggesting that this dorsal position of the seta subdentalis may be a synapomorphy for the Pseudochironomini. Ecology and biogeography The larvae of M. obscura live in rain-fed and groundwater-fed shallow-water habitats near rivers that are subject to considerable water-level fluctuation (Fittkau 1963). The larvae construct 25–35-mm-long tubes, which are upright during higher water stages but recline onto the bottom when water levels diminish to just a thin film. Larvae possess elongated, extensively tracheated anal tubules, large plural bulges on segments IV–X, lateral tubules on segments VIII and IX, and a long curved procercus. All of these features are thought to facilitate respiration within tubes when water levels decline. The pupae also have a dramatically elongated thoracic horn that may facilitate respiration when water levels are low. The precise habit and microhabitat of M. pahayokeensis larvae have not yet been discovered. Collection records suggest its ecology may be similar to that of M. obscura from Amazonian riverside pools. All collection sites for M. pahayokeensis experience water-level fluctuations and seasonal drying, and were shallow (,20 cm) at the time of collection. They also had fairly uniform soil depths, or at least a lack of limestone outcropping, and often dense growth of mixed grassy vegetation that inhibited the filamentous

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cyanobacterial periphyton growth that is widespread at marl prairie sites in the Everglades. Most specimens were collected at the end of the rainy season in September and October from sites along the margins of Taylor Slough that are wetted, on average, for ,6 mo/y. However, specimens were also collected from the main channel of the slough at the onset of the rainy season in June when water levels were low but starting to rise. Thus, populations may be able to move about and exploit other suitable habitats when they become seasonally available. Hydrological patterns in Taylor Slough have been altered since canals and levees were constructed and the eastern Everglades were overdrained in the last century. At present, water levels are artificially maintained by a system of canals and pumps along the eastern edge of Everglades National Park. Cessation of pumping into Taylor Slough usually occurs in late winter and results in sudden, sharp declines in water levels at sites where M. pahayokeensis has been collected. Though Manoa may be adapted for water-level fluctuation, the effect of these unnaturally rapid water-level drops on populations of M. pahayokeensis needs to be assessed through manipulative experimentation when the larval microhabitat is discovered. Manoa pahayokeensis is perhaps the most unusual of a group of species in the Everglades belonging to chironomid genera with primarily Neotropical or pantropical distributions. Other tropical genera in Everglades National Park include: Goeldichironomus (4–5 spp.), Beardius (3 spp., Jacobsen and Perry 2000), Endotribelos (1 sp.), Polypedilum (Asheum) (1 sp.), Coelotanypus Kieffer (1 sp.), and Fittkauimyia Karunakaran (1 sp.). In addition, other genera present, such as Labrundinia Fittkau (8 spp.), Pseudochironomus (3 spp.), and Parachironomus Lenz (4 spp.), are found throughout the Holarctic, but show their greatest diversity in the Neotropics (Roback 1987, Andersen and Sæther 1997, Sublette and Mulla 2000). Those genera with strictly PanAmerican distributions (Goeldichironomus, Beardius, Endotribelos, and Polypedilum (Asheum)) likely moved from South America northward into the Nearctic across either the Antilles or along the Central American and Mexican coastal plains (Reiss and Sublette 1985, Ashe et al. 1987, Sublette and Mulla 2000). The more widespread distributions of other tropical genera in south Florida invoke more speculative scenarios in-

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volving Gondwanan origin, vicariance, and dispersion (Sæther 2000). Collection records for Manoa suggest the genus originated in Gondwanaland prior to the separation of Africa and South America (Andersen and Sæther 1997). Dispersal to the Nearctic and eventually south Florida from South America could have followed the 2 general northerly tracks mentioned above. However, Sæther (1981, 1982) noted similarities between the Orthocladiinae of the British West Indies and southeast United States with those of Africa, and suggested significant direct exchange of fauna may have occurred between these regions through tectonic vicariance events and dispersal. Acknowledgements We thank Peter Cranston, William P. Coffman, John H. Epler, Leonard Ferrington, Ralph Holzenthal, and Ole A. Sæther for their reviews, comments, and editing on early drafts of this manuscript, and David M. Rosenberg for editing the final draft. We also thank Peter Cranston for sharing unpublished information on the morphology of Riethia. Funding for REJ was provided through Cooperative Agreement No. 5280-8-9015 from Everglades National Park, National Park Service, to Kelsey Downum, Chair, Department of Biological Sciences, Florida International University, Miami, Florida, USA. This contribution is part of a larger study of invertebrates in eastern Everglades National Park that was funded by the Critical Ecosystems Science Initiative of the National Park Service. Literature Cited ANDERSEN, T., AND O. A. SÆTHER. 1997. First record of Manoa Fittkau and tribe Pseudochironomini Sæther from the Afrotropical region (Diptera: Chironomidae: Chironominae). Entomologica Scandinavica 28:311–317. ASHE, P., D. A. MURRAY, AND F. REISS. 1987. The zoogeographical distribution of Chironomidae (Insecta: Diptera). Annales de Limnologie 23:27–60. FITTKAU, E. J. 1963. Manoa, eine neue Gattung der Chironomidae (Diptera) aus Zentralamazonien. Chironomidenstudien IX. Archiv fu¨r Hydrobiologie 59:373–390. GUNDERSON, L. H., AND W. F. LOFTUS. 1993. The Everglades. Pages 199–255 in W. H. Martin, S. G. Boyce, and A. C. Echternacht (editors). Biodiversity of the Southeastern United States: lowland

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terrestrial communities. John Wiley and Sons, New York. JACOBSEN, R. E., AND S. A. PERRY. 2000. A review of Beardius Reiss and Sublette, with description of a new species from Everglades National Park (Insecta, Diptera, Chironomidae). Pages 129–144 in M. Baehr and M. Spies (editors). Contributions to chironomid research in memory of Dr Friedrich Reiss. Spixiana 23. LANGTON, P. H. 1994. If not ‘‘filaments’’, then what? Chironomus 6:9. LANGTON, P. H. 2000. What’s the point? Chironomus 13: 19. LENCZEWSKI, B. 1980. Butterflies of Everglades National Park. South Florida Research Center Technical Report T-588. Everglades National Park, National Park Service, Homestead, Florida. PAULSON, D. R. 1966. The dragonflies (Odonata: Anisoptera) of Southern Florida. PhD Dissertation, University of Miami, Coral Gables, Florida. PINDER, L. C. V., AND F. REISS. 1983. 10. The larvae of Chironominae (Diptera: Chironomidae) of the Holarctic region—Keys and diagnoses. Pages 293–435 in T. Wiederholm (editor). Chironomidae of the Holarctic region. Keys and diagnoses. Part 1. Larvae. Entomologica Scandinavica Supplement 19. REISS, F., AND J. E. SUBLETTE. 1985. Beardius new genus with notes on additional Pan-American taxa (Diptera, Chironomidae). Spixiana, Supplement 11:179–193. ROBACK. S. S. 1987. The immature chironomids of the eastern United States. IX. Pentaneurini—Genus Labrundinia with the description of some Neotropical material. Proceedings of the Academy of Natural Sciences of Philadelphia 139:159–209. SÆTHER, O. A. 1977a. Taxonomic studies on Chiro-

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nomidae: Nanocladius, Pseudochironomus, and the Harnischia complex. Bulletin of the Fisheries Research Board of Canada 196. SÆTHER, O. A. 1977b. Female genitalia in Chironomidae and other Nematocera: morphology, phylogenies, keys. Bulletin of the Fisheries Research Board of Canada 197. SÆTHER, O. A. 1980. Glossary of chironomid terminology (Diptera: Chironomidae). Entomologica Scandinavica, Supplement 14. SÆTHER, O. A. 1981. Orthocladiinae (Diptera: Chironomidae) from the British West Indies, with descriptions of Antillocladius n. gen., Lipurometriocnemus n. gen., Compterosmittia n. gen. and Diplosmittia n. gen. Entomologica Scandinavica, Supplement 16. SÆTHER, O. A. 1982. Orthocladiinae (Diptera: Chironomidae) from SE USA., with descriptions of Plhudsonia, Unniella and Platysmittia n. genera and Atelopodella n. subgen. Entomologica Scandinavica 13:465–510. SÆTHER, O. A. 2000. Zoogeographical patterns in Chironomidae (Diptera). Verhandlungen der Internationalen Vereinigung fu¨r theoretische und angewandte Limnologie 27:290–302. SOPONIS, A. R. 1977. A revision of the Nearctic species of Orthocladius (Orthocladius) van der Wulp (Diptera: Chironomidae). Memoirs of the Entomological Society of Canada 102. SUBLETTE, J. E., AND M. S. MULLA. 2000. Chironomus strenzkei Fittkau—a new Pan-American distribution, with a review of recent similar additions to the Nearctic midges. Pages 145–149 in M. Baehr and M. Spies (editors). Contributions to chironomid research in memory of Dr Friedrich Reiss. Spixiana 23. Received: 30 January 2001 Accepted: 21 December 2001