THEAFRO-ASIAN MESOCYCLOPSASPERICORNIS (DADAY) (COPEPODA,CYCLOPIDAE) IN MEXICO: COMMENTSON MORPHOLOGYANDDISTRIBUTION

BY

MARTHA ANGÉLICA GUTIÉRREZ-AGUIRRE 1/,EDUARDO SUÁREZ-MORALES 1,3/ andMARCELO SILVA-BRIANO 2/ 1/ El Colegiode la FronteraSur (ECOSUR), A.P.424,77000 Chetumal, Quintana Roo, Mexico 2/ UniversidadAutó noma de Aguascalientes Biologí a (C.Ciencias Bá sicas), Centrode Ciencias Bá sicas, A v.Universidad 940, Fracc. Primo V erdad,20100 Aguascalientes, Aguascalientes,Mexico

ABSTRACT Theknown distribution of Mesocyclopsaspericornis inthe Americas included the central and northernareas of South America and the insular Caribbean. It had not been collected before in continentalNorth America. The analysis of samplescollected in a pondin the state of Sinaloa, on thePaciŽ c coastof Mexico, yielded female individuals of this species. The Mexican individuals tendedto besmallerthan the African females (1.14-1.20 mm vs1.3-1.5mm), but the morphology ofthe Mexican specimens is identical in mostcharacters to thatdescribed or depicted in previous works.This is the Ž rstmorphological study of this species aided with SEM; itincludes detailed dataon severalmicrostructures, some of which undescribed previously. It alsois the Ž rstreport of its effectiveoccurrence in Mexico.All previous records of this species in theAmericas are related to the Atlanticcoasts. This record, in theMexican PaciŽ c area,suggests that this supposedly introduced Afro-Asianspecies had an alternative route of dispersion from the PaciŽ c coast.This is also the seconddocumented record of an introducedfreshwater copepod in Mexico.

RESUMEN Ladistribució n conocidade Mesocyclopsaspericornis enel continente americano incluí a las areassur y centralde Amé rica del Sur y delCaribe insular. No habí a sidorecolectada antes en América del Norte. El análisis de muestras recolectadas en unestanque en el estadode Sinaloa, costa pacíŽ cadeMéxico, produjo la identiŽ cació n dehembras de estaespecie. Las hembras recolectadas enMé xico tiended a serde menor talla que las africanas (1.14-1.20 mm vs1.3-1.5mm); sin embargo, lamorfologí a delosespecí menes mexicanos es idé ntica en prácticamente todos los caracteres a las descripcionesprevias. Este es, sin embargo, el primerestudio morfoló gico auxiliado por microscopí a electrónica de barrido (MEB); incluye datos detallados sobre varias microestructuras, algunas previamenteindescritas. Este es el primer registro efectivo de la presencia de estaespecie en Mé xico;

3/ e-mail:[email protected] © KoninklijkeBrill NV ,Leiden,200 3 Crustaceana 75(11):1349-1361 Alsoavailable online: www.brill.nl 1350 M.A.GUTIÉ RREZ-AGUIRRE, E. SUÁREZ-MORALES & M.SILVA-BRIANO todoslos registros anteriores estaban relacionados con las costas del Océ ano Atlá ntico. Este registro enelá readel Pací Ž coMexicano sugiere que esta especie Afro-asiá tica supuestamente introducida tuvouna ví a alternativade dispersió n apartirde la costa del Pací Ž coTropical Oriental. Este es, además, elsegundo registro documentado de unaespecie de copé podo dulceacuí cola introducida en México.

INTRODUCTION Thefreshwater cyclopoidcopepod Mesocyclopsaspericornis (Von Daday, 1906)is awidespreadpantropical species knownmainly fromAsia (India,China, Birma ( Myanmar),the Philippines, Java,Sumatra) andAfrica (Ethiopia,Ghana, D Zaire ( Congo),Sudan, Nigeria) (Dussart &Defaye,1985; V ande Velde,1984). D InAmerica, this species has beenrecorded from various Neotropical areas, includingthe insular Caribbean(Martinica, Guadeloupe,Aruba, Curaç ao, Puerto Rico,Haiti, Turksand Caicos Islands, VirginIslands, Jamaica, amongothers) andSouth America (Brazil, Colombia,V enezuela,Argentina) (see Pesce, 1985; Reid,1990; Reid &Saunders,1986; Rocha & Botelho,1998). The study of its distribution is arelevant issue, since this species has beentested successfully as a biological controlof mosquitolarvae in the neotropics(Suá rez et al., 1984;Marten et al., 1994). Despite its widedistribution inthe tropical areas, this species hadnot been recordedfrom continental NorthAmerica (Williamson &Reid,2001), including Mexicoand Central America.A previousrecord listed bySuá rez-Morales &Reid (1998)from Aguascalientes, central Mexico,is consideredinvalid (see Dodson &Silva-Briano,1996; Silva-Briano, pers. obs.). The occurrence of this species inMexico was also outlinedby Suárez-Morales &Gutiérrez-Aguirre (2001) in a project report.From samples collected in asmall reservoir in the state ofSinaloa, onthe PaciŽc coast ofMexico, the occurrenceof Mesocyclopsaspericornis is now effectively reportedherein. The Mexican specimens wereexamined using both light microscopyand SEM in orderto providecomplementary morphological data forthe species.

MATERIALS AND METHODS Zooplanktonsamples werecollected in asmall reservoir (“bordo”) located nearkm 90 of the highwayCuliacá n-Los Mochis, in Sinaloa,Mexico (25 ±170N 107±470W).Samples werecollected on20 November 1985 by Alejandro Maeda- Martínez and Hortencia Obregó n-Barboza with the aid ofascoopnet with amesh size of0.05mm. The specimens weresorted fromthe entire sample andidentiŽ ed usingthe descriptions andkeys of V ande V elde (1984)and Ho€ y nska´ (2000). MESOCYCLOPSASPERICORNIS (DADAY)INMEXICO 1351

Someindividuals were processed for SEM analysis andthe remainingones were preservedin 70% ethanol. Morphological observations were made under a standard microscopeand SEM analysis was performedusing a Topconelectron microscope (10-16kV).Line illustrations weremade using a camera lucida.

RESULTSAND DISCUSSION Onlyfemale specimens of Mesocyclopsaspericornis werecollected in Sinaloa (Silva-Briano,pers. obs.), which were part ofanisolated population.Males ofthis species werenot found in the samples. This is notuncommon, as males ofthis species are notfound often (see Reid& Saunders,1986) and morphological data are still limited.

Morphology Someof the main morphologicalcharacters ofthe Mexicanfemale specimens of M.aspericornis are presentedin Žgs.1-6; these includeboth line drawings andSEM photographs.The morphology of the specimens fromMexico agrees in generalwith the descriptions ofKiefer (1981),V ande Velde (1984),and Ho€ y nska´ (2000),even in the structure andornamentation of the mouthparts(Ž gs. 2B-D, 3A-D)and swimming legs (Žgs. 3E, 4A-C). The South American specimens, exceptthe Brazilian material, lack the pits onthe lateral surfaces ofthe genital somite whichwere depicted by Kiefer (1981)for African specimens (Reid & Saunders,1986). As stated byHo€y nska´ (2000) for Asian specimens, SEManalysis conŽrmed that in the Mexicanindividuals the entire ventral anddorsal surfaces of the genital somite are pitted (Žgs. 1A, D, F,5D),not only the lateral margins as describedby Kiefer (1981)and Pesce (1985).Therefore, the Brazilian, Mexican, andAsian specimens differ in this character fromthe (remaining)South American specimens. Wereport here the presenceof a large poresurrounded by an other Žvepores on the surface posterior ofthe plate ofthe sixth leg; this was evident onlythrough SEM observation(see Žg.6A). This character remainedpreviously unnoticed,its taxonomicvalue has notyet beenexplored. TheMexican material showssome differences with respect to the African andAsian specimens (Kiefer,1981; V ande V elde,1984; Ho€ y nska,´ 2000). The Mexicanfemales tendedto be smaller thanthe Africanones (1.14-1.20 mm vs 1.3-1.5mm). In our specimens, the pitted antennularsegments are 1,4,5, and 7- 16,versus the 1-6,14-16 pattern describedby Kiefer (1981).This character was not describedby V ande Velde (1984)or Ho€y nska´ (2000). The spine-bearing segments (Žg. 2A) and the hyalinemembrane on the last segment (Žg. 5A) are identically built in the Mexicanand in the Africanand Asian specimens (Vande V elde,1984; 1352 M.A.GUTIÉ RREZ-AGUIRRE, E. SUÁREZ-MORALES & M.SILVA-BRIANO

Fig. 1. Mesocyclopsaspericornis (Daday,1906), adult female from Sinaloa, Mexico. A, urosomeand caudal rami, dorsal; B, Žfthleg; C, analsomite and left caudal ramus, ventral; D, genitalsomite, ventral; E, analsomite and right caudal rami, dorsal; F ,habitus,dorsal. All scale linesrepresent 50 ¹m. MESOCYCLOPSASPERICORNIS (DADAY)INMEXICO 1353

Fig. 2. Mesocyclopsaspericornis (Daday,1906), adult female from Sinaloa, Mexico. A, antennule;B, mandiblewith gnathal edge; C, maxilla;D, maxilliped.All scale lines represent 50 ¹m. 1354 M.A.GUTIÉ RREZ-AGUIRRE, E. SUÁREZ-MORALES & M.SILVA-BRIANO

Fig. 3. Mesocyclopsaspericornis (Daday,1906), adult female from Sinaloa, Mexico. A, antennal basipodite,frontal; B, antennalbasipodite, caudal; C, maxillule;D, maxillularpalp; E, Žrstleg, endopoditeseparated, frontal. All scale lines represent 50 ¹m. MESOCYCLOPSASPERICORNIS (DADAY)INMEXICO 1355

Fig. 4. Mesocyclopsaspericornis (Daday,1906), adult female from Sinaloa, Mexico. A, secondleg, caudal;B, thirdleg, caudal; C, fourthleg, caudal. All scale lines represent 50 ¹m. 1356 M.A.GUTIÉ RREZ-AGUIRRE, E. SUÁREZ-MORALES & M.SILVA-BRIANO s r n e a a l i e s h u n e c n a A t i s t o p e ) e d s n s n 0 n i l f 0 r a p a o n e 0 t ) s o d s 2 d 3 d d 4 f i i ( w n t e e e 1 8 o d o r e - a b b b 9 r l , e i i i s 7 k s 1 6 r r r s d . p e s , 0 5 6 , c c c f n e ) ´ . 1 . . u u n 5 i s s t s e o - a 3 1 3 o q y , e a e e i d i - 1 - - r € p r l s d 4 d d l l r w 1 4 1 9 7 g o e n . n b . n , . . . a e A o V H ( 1 u 1 u s 2 1 0 u 2 3 p r o e d n a V r ; a 1 e 8 ) h n 9 4 c t s 1 8 o e , 9 r n n 1 i e l ( f p a n e e t s i s o d 3 d d d f i i l ) t e e e K 1 o d e r ( y - b b b 1 5 , e a i i i s V 7 ) 3 4 n r r s r d d . . p , a a c 5 c c e n e a 1 . 3 u c 5 i s t s s c d i - - i 2 o e , a e e D r r 8 - 3 7 7 r p r ( n f d 4 d d f l r 4 2 9 1 4 8 3 g a . n , ...... a n n s e A A i u 1 s 1 0 V ( 1 1 2 0 3 3 p u u n f r o o s c i n r o i e t p r p s a i r a e h c n s c s t p s e o o e d l n n c i d l y p e ) a I n c t s h 1 o s o d d d s f i i 8 E i s t e e e l o 6 d 9 r e L b b b b 1 , 1 e i i s i ) - ( r s r r u M B d p a 4 c c c p n r e f u c i A t s s s 1 e i o 5 o h e a e e f r , . T 5 3 r t p r f s e d d d i l 6 r 3 5 2 1 1 g i n n . . a . - . - n n e A w e K ( 1 1 u 1 s 3 1 1 1 3 3 p u u s m n i e c e m p i s c e , ) a p 0 s r s o 0 l e a l 0 n a e h u 2 a n n e c i n c , a t i i s t S a o p x e e k n s e n s s m i l f ´ r n o p M a o n e r y t s € f f o s d 6 3 f i i o o w n s t 1 1 4 o d r o e - - s n H 1 l r , e r s ( e : 7 7 s 2 s e d . p e o 0 , , t 7 5 f e n m c . 1 . u u 5 5 i c i t i o - o 2 3 q a a c § , , x i 7 - 5 5 - r p r r e l 4 4 l e r w 2 1 g a 6 5 3 1 p : , , . . . . . a b e o h S M s 1 3 o 1 1 1 1 2 1 1 3 p r c c i m o n o 5 x g a 4 h t e 5 t l t i g g , n 4 e w e a l l l f f a l t a a g s s o , o a v e , c c t t r e e e s i i x a l l o o n n a ) e t n 7 p p l o i i l , e i e e n t e t a a a c r 1 u m i d s p / a a l n m m n f r s r s o e h h l h m 6 a m y g g t t t i n o u a p ( r a 1 y h h s e e e e g g g x e c x t o t s s t h n , m t i h s n n n n o o d d d t t n a o r d u a i p i e e e e e e c n r g a n l l l s r l l l e a p e o i e e w / / w l r / l n b u u f u f f f p r / / d r e e e a i a b e a n n n o o o o d l l e m h h i l e m n n n c l l t t r t p n n n i i i r d i i g t e i n l o o o o g g e i e e i p i e i p i p u n x x a h n t t t m t t t t n n t p s s m t i s s f a a a n n n o a a a a e e o C T A A R A L R R R L M M M MESOCYCLOPSASPERICORNIS (DADAY)INMEXICO 1357

Fig. 5. Mesocyclopsaspericornis (Daday,1906), adult female from Sinaloa, Mexico. A, detail ofhyaline membrane on last antennular segment; B, labrum,ventral; C, maxillarcoxa, detail of ornamentation;D, Žfthleg, detail of distalend of medialspine (SEM).

Ho€ynska,´ 2000). However, the antennularsegment 16tends to berelatively longer in the Mexicanmaterial (see table I).W efoundno relevant differences in the proportionsof the structures oflegs 4and5 (see table I)(Žg. 4C).However, the proportionallength of the terminal spine/proximalseta ofthe Žfth leg (Žg. 1B) is about30% higher in the Mexicanspecimens. Thereare similarities betweenthese twogroups of specimens inseveral minor details andproportions. The furcal length/widthratio values ofthe Mexican material (Žg. 1C, E) fall well within the rangedescribed for the Africanand Asian material (see table I).The ornamentationof the mandibles,not described by Kiefer (1981)or V ande Velde (1984),was Žrst depictedby Ho€ y nska´ (2000) and includes three groupsof spines nearthe insertion ofthe palp; this character is present in the Sinaloa specimens as well (Žg. 2B). The same is true forthe maxillae, whichhave asingle rowof slender setae onthe coxalsurface in bothgroups of specimens (table I)(Žgs. 2C, 5C). We observed the obliquerow of minute spinules onthe syncoxalsurface ofthe maxilliped as reportedby Ho€ y nska´ (2000). As inthe South 1358 M.A.GUTIÉ RREZ-AGUIRRE, E. SUÁREZ-MORALES & M.SILVA-BRIANO

Fig. 6. Mesocyclopsaspericornis (Daday,1906), adult female from Sinaloa, Mexico. A, detailof poreson posterior surface of sixth leg plate; B, Žfthpediger and genital somite, ventral; C, anal somite,ventral; D, analsomite, dorsal (SEM).

Americanspecimens (see Reid &Saunders,1986), the Mexicanfemales possess several rowsof small pits onthe dorsal surface ofthe Žrst antennularsegment. Reid& Saunders(1986) recommended the use ofSEMinorder to studysome ofthe smallest cuticular structures ofthis species. It was clear that the use of SEMprovideda moredetailed overviewof the micromorphologyof this species; however,a similar analysis still has to beperformed on the rarely foundmale specimens.

Distribution

Theknown latitudinal rangeof this species extendsfrom the 33 ±N to 28±S, thus includingvarious subtropical areas ofthe world.In the Americas, this species rangesroughly between 21 ±490N(Caicos Islands) (Pesce, 1985)and 28 ±S (middle Paranáriver, Argentina) (Dussart &Frutos,1985). Hence, the northernmostlimit ofthe knowndistributional rangeof this species in the Americas is expanded with this record,settting the northernmostlimit of Mesocyclopsaspericornis well beyond 25±Nin Sinaloa,Mexico. MESOCYCLOPSASPERICORNIS (DADAY)INMEXICO 1359

Most ofthe Americanrecords of M.aspericornis relate to the Atlantic coast (Caribbeanislands, VenezuelanCaribbean, eastern coast ofBrazil, Argentina).W e consideredthis species tobe an introduced form (Reid &Pinto-Coelho,1994), clearly morerelated to the African-Asianspecies of Mesocyclops (see Van de Velde,1984; Ho€ y nska,´ 2000). There are three morphologicalfeatures sharedby most African(67%) and Asian (87%)species of Mesocyclops :the absenceof spines nextto the insertion ofthe exopodon the antennalbasipodite, the absence ofa spine orseta onthe innerbasis in the Žrst leg,and the widelateral arms ofthe seminal receptacle, formingan anterior, deeply concave (or even V -shaped)margin (see Vande V elde,1984; Ho€ y nska,´ 2000). These features are clearly present in M.aspericornis ,too;hence, we speculate that it was originally anOld World form.This hypothesisis supportedby twofacts: (1)only 17% of the NewW orld Mesocyclops bearthese features; oneof these ( M. ogunnus Onabamiro,1957) was recordedas anintroduced species inBrazil (Reid &Pinto-Coelho,1994). (2)The corresponding three features mentionedabove are contraryto those ofthe American Mesocyclops (65%):presence of spines nextto the exopodalinsertion onthe basis ofthe antenna,presence of aseta onthe innerbasis inthe Žrst leg,and the lateral parts ofthe seminal receptacle narrow,with anterior marginweakly concaveor strongly convex (see Dussart, 1981;Suá rez-Morales &Gutiérrez- Aguirre,2001). Although we haveno sound evidence to decidewhich feature is derived,it remains clear that these three characters canbe useful toseparate Old andNew W orld Mesocyclops . Therefore,considering its origin,distribution, andthe previousrecords, we think that the introductionof M.aspericornis started somewherealong the Atlantic coast ofAmerica, from where this fugitive species (Reid &Saunders,1986) dispersed in variousdirections. Theunexpected record on the MexicanPaciŽ c coast suggests bothan alternative starting pointfor dispersal anda recent dispersal process, because(1) this large,conspicuous species has notbeen recorded previously in Mexico,neither in the southernnor in the central parts, whichhave been surveyed forseveral decades(Suá rez-Morales et al., 1996;Suá rez-Morales &Reid,1998). (2)Sinaloa is ahighlyactive area foraquaculture, an activity widelyknown as oneof the main causes favouringthe introductionof an exotic copepodfauna (Reid &Pinto-Coelho,1994). Hence, this is consideredto bethe secondrecord of anintroduced species inMexico after Thermocyclopscrassus (Fischer, 1853)(cf. Gutiérrez-Aguirre & Suárez-Morales, 2000).Other introduced species suchas the Afro-Asian Mesocyclopsogunnus (cf.Suá rez-Morales et al., 1999)and T. crassus havebeen recorded along the Atlantic coast ofthe Americas. 1360 M.A.GUTIÉ RREZ-AGUIRRE, E. SUÁREZ-MORALES & M.SILVA-BRIANO

Ecology Mesocyclopsaspericornis has beencollected froma widevariety ofNeotropical freshwater environments.These include extreme habitats, fromsmall containers of onlya fewliters to large lakes (see Reid &Saunders,1986). Hence, the temporal cattle wateringpond surveyed in Sinaloa, with its small volume(0.35 m deep)is, ofcourse,within these limits. Accordingto Reid &Saunders(1986), the species is anepibenthic form dwelling in the littoral zones.The discovery of apopulationof M.aspericornis in this clay bottom,shallow pondseems to supportthis statement.

ACKNOWLEDGEMENTS This workis part ofthe doctoralproject ofthe Žrst author(MG-A) to review the taxonomyof the species of Mesocyclops distributed in the neotropics.We gratefully acknowledgethe conŽdence of Alejandro Maeda-Martí nez (CIBNOR, LaPaz,Mexico) for granting us the samples ofthe “bordo”at km90in Sinaloa, Mexico.

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Firstreceived 1 May2002. Finalversion accepted 21 June 2002.