SEAVR 2022: 028‐029
ISSN: 2424‐8525
Date of publication: 13 December 2022
Hosted online by ecologyasia.com

Interspecific amplexus between Kalophrynus sinensis (Peters 1867) andPulchrana grandocula (Taylor 1920) in Rogongon, Iligan City, Philippines
Andrie Bon A. FLORES, Rieneth R. PANTORILLA & Olga M. NUŇEZA
andriebonflores@g.msuiit.edu.ph (Flores)

Observers: Andrie Bon A. Flores, Rieneth Pantorilla.
Photograph by: Andrie Bon A. Flores.
Subjects identified by: Andrie Bon A. Flores.
Location: Sitio Libandayan, Barangay Rogongon, Iligan City, Mindanao, Philippines.
Elevation: 791 metres ASL.
Habitat: Pond, Secondary forest.
Date and time: 19 March 2022, 19:15 hrs.s
Identity of subjects:i) Black‐spotted Sticky Frog/ Philippine Sticky Frog, Kalophrynus sinensis (Amphibia: Anura: Microhylidae).
ii) Big‐eyed Frog, Pulchrana grandocula (Amphibia: Anura: Ranidae).
Description of record:
During a herpetological survey we observed an interspecific amplexus between two different anurans, namely
Black‐spotted Sticky Frog (Kalophrynus pleurostigma) and Big‐eyed Frog (Pulchrana grandocula) (Fig. 1). They were
found near a pond where Pulchrana grandocula was abundant. No eggs were produced at the time of observation.

Fig. 1. Kalophrynus sinensis (above) and Pulchrana grandocula (below)

28© Andrie Bon A. Flores

Remarks:
The upper frog (assumed to be male) was identified as Kalophrynus sinensis because it is a microhylid with distinct
traits which are (i) having black spots on its back, (ii) a light edged ocellus, (iii) existence of middorsal stripe fromsnout to neck where it bifurcates, (iv) coarsely granular body on dorsal and ventral section, (v) well developed
subarticular tubercles, (vi) lack of webbing on fingers with slightly swollen and rounded tips but has webbed toes,(vii) dorsolateral ridge distinct from shoulder to inguinal area, and (viii) granular rugose dorsal surface (Inger 1954and Zug 2015). This species is endemic to the Philippine Islands.
The lower frog (assumed to be female) was identified as Pulchrana grandocula which is a relatively medium‐sized
ranid that has (i) a slender body, (ii) long legs, (iii), smooth dorsal skin with dorsolateral skin folds, (iii) digit tips arerounded with webbed toes, and (iv) big eyes. This species can be found on tree branches and leaves, on rocks, onrotten logs in or along rivers and streams, and amid rotting leaves on the forest floor near rivers in cultivatedregions, secondary, and dipterocarp woods (Plaza & Sanguila, 2015). This species is endemic to the Mindanao
Pleistocene Aggregate Island Complex (PAIC) region (Sanguila et al., 2016).
Anurans have a wide range of intricate mating behaviors. Male frogs start the process by making species‐specificmating sounds or advertisement calls that attract females of the same species. The male then performs amplexus,
in which he grasps the female with his front legs, fertilizing the eggs laid by the female. However, mating between
them can be a deviation such as interspecific amplexus (Vivek et al., 2014), which can occur when two different
species' reproductive activity overlaps in space and time, when niche segregation between species is absent, when
there is a reduced number of females, and even when there is a release of confusing chemical signals (Höbel, 2005).
This phenomenon appears relatively uncommon in frogs, given the low number of published notes andobservations (Groffen et al., 2019). In this case, our observation shows that the interspecific amplexus between
Kalophrynus sinensis and Pulchrana grandocula can be explained by the overlap of space and time, since they arefound in the same area. Other interspecific amplexus events have been observed in the Philippines (e.g. Lorenzo &Ralubit, 2019) however, to our knowledge, this is the first record of observation of the interspecific amplexus
between these two Philippine endemic frogs Kalophrynus pleurostigma and Pulchrana grandocula.

References:Inger, R. F. (1954). Systematics and zoogeography of Philippine Amphibia. Fieldiana Zool, 33, 181‐531.
Groffen, J., Yang, Y., Borzée, A., & Jang, Y. (2019). Interspecific amplexus between Glandirana tientaiensis (Chang,1933) and Odorrana schmackeri (Boettger, 1892) at the Fuchun River, eastern China. Herpetology Notes, 12, 41‐42.
Höbel, G. (2005). Natural history notes. Rana clamitans (Green Frog) and Rana catesbeiana (American Bullfrog).
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Vivek, S., Dinesh, M., Kumar, K. R., Divaker, Y., & Sharma, K. K. (2014). Interspecies mating interactions between
Duttaphrynus stomaticus (Marbled Toad) and Sphaerotheca breviceps (Indian burrowing frog) at the central Aravalli
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Zug, G. (2020). Morphology and systematics of Kalophrynus interlineatus‐pleurostigma populations (Anura:Microhylidae: Kalophryninae) and a taxonomy of the genus Kalophrynus Tschudi, Asian Sticky Frogs. Proceeding ofthe California Academy of Sciences 62(4): 135–190.

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