I have created custom module and update layout for catalog product listing page and product detail page shown below.

<layout version="0.1.0">
<catalog_product_view translate="label">
        <reference name="product.info.addtocart">
            <block type="core/template" name="mytest" template="mytest/mytest.phtml"/>
        </reference>
        <reference name="product.info.additional">
            <block type="core/template" name="mytest"
                   template="mytest/mytest.phtml"/>
        </reference>
    </catalog_product_view>
    <catalog_category_layered translate="label">
        <reference name="product.info.addtocart">
            <block type="core/template" name="mytest" template="mytest/mytest.phtml"/>
        </reference>
        <reference name="product.info.additional">
            <block type="core/template" name="mytest"
                   template="mytest/mytest.phtml"/>
        </reference>
    </catalog_category_layered>
</layout>

Its working fine for product detail page but it won't work on catalog product listing page.

Please advice me how to add custom block under the product price/Add Cart button in product listing page?